U.S. patent application number 14/572556 was filed with the patent office on 2015-06-25 for preserving genomic connectivity information in fragmented genomic dna samples.
This patent application is currently assigned to ILLUMINA, INC.. The applicant listed for this patent is ILLUMINA, INC.. Invention is credited to Sasan AMINI, Jeffrey S. FISHER, Kevin L. GUNDERSON, Frank J. STEEMERS.
Application Number | 20150176071 14/572556 |
Document ID | / |
Family ID | 52293249 |
Filed Date | 2015-06-25 |
United States Patent
Application |
20150176071 |
Kind Code |
A1 |
FISHER; Jeffrey S. ; et
al. |
June 25, 2015 |
PRESERVING GENOMIC CONNECTIVITY INFORMATION IN FRAGMENTED GENOMIC
DNA SAMPLES
Abstract
A method of sequencing a target nucleic acid polymer by (a)
modifying a target nucleic acid polymer to produce a modified
nucleic acid polymer; (b) producing fragments of the modified
nucleic acid polymer, wherein the fragments are attached to
locations on a solid support surface (c) determining nucleotide
sequences from the fragments at the locations; and (d) producing a
representation of the nucleotide sequence for the target nucleic
acid polymer based on the nucleotide sequences from the fragments
and the relative distances between the locations on the solid
support surface.
Inventors: |
FISHER; Jeffrey S.; (San
Diego, CA) ; STEEMERS; Frank J.; (Encinitas, CA)
; AMINI; Sasan; (Redwood City, CA) ; GUNDERSON;
Kevin L.; (Encinitas, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ILLUMINA, INC. |
San Diego |
CA |
US |
|
|
Assignee: |
ILLUMINA, INC.
San Diego
CA
|
Family ID: |
52293249 |
Appl. No.: |
14/572556 |
Filed: |
December 16, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61935776 |
Feb 4, 2014 |
|
|
|
61919529 |
Dec 20, 2013 |
|
|
|
Current U.S.
Class: |
506/2 |
Current CPC
Class: |
C12Q 1/6874 20130101;
G16B 30/00 20190201; C12Q 1/6874 20130101; C12Q 2535/119 20130101;
C12Q 2535/122 20130101; C12Q 2565/513 20130101; C12Q 2565/543
20130101 |
International
Class: |
C12Q 1/68 20060101
C12Q001/68 |
Claims
1. A method of sequencing a target nucleic acid polymer, comprising
(a) modifying a target nucleic acid polymer to produce a modified
nucleic acid polymer, wherein the modified nucleic acid polymer
comprises a plurality of sequence regions from the target nucleic
acid polymer; (b) producing fragments of the modified nucleic acid
polymer in a vessel comprising a solid support surface, each
fragment comprising one of the sequence regions; (c) capturing the
fragments randomly at locations in a region of the solid support
surface; (d) determining nucleotide sequences of the sequence
regions by detecting the fragments at the locations; and (e)
producing a representation of the nucleotide sequence for the
target nucleic acid polymer based on the nucleotide sequences from
the fragments and the relative distances between the locations on
the solid support surface.
2. The method of claim 1, wherein the modifying comprises adding
inserts into the target nucleic acid polymer to form the modified
nucleic acid polymer, wherein the modified nucleic acid polymer
comprises a plurality of internal inserts.
3. The method of claim 2, wherein the fragments produced in step
(b) each comprise at least a portion of an insert added in step
(a).
4. The method of claim 3, wherein the inserts further comprise
cleavage sites and wherein producing of the fragments in step (b)
comprises cleaving the inserts at the cleavage sites.
5. The method of claim 2, wherein the inserts have priming sites;
wherein the fragments each comprise at least a portion of the
inserts having the priming sites; and wherein step (d) comprises
determining nucleotide sequences from the fragments by extension of
primers hybridized to the priming sites at the locations.
6. The method of claim 2, wherein the inserts comprise ligands that
attach to receptors on the solid support surface.
7. The method of claim 2, wherein the inserts are added into the
target nucleic acid polymer by transposases.
8. The method of claim 7, wherein each of the inserts comprise a
first transposon element and a second transposon element that is
contiguous with the first transposon element; and wherein a
transposase associated with the first transposon element and the
second transposon element forming transposomes.
9. The method of claim 8, wherein the 5' end of the first
transposon element is attached to the 5' end of the second
transposon by a linker.
10. The method of claim 8, wherein the first transposon element and
the second transposon element each comprise forked adapters.
11. The method of claim 8, wherein the transposases comprise
ligands and the surface comprises receptors that bind to the
ligands to attach the modified nucleic acid polymer to the surface
prior to the producing of the fragments.
12. The method of claim 7, wherein step (b) comprises attaching the
modified nucleic acid polymer to the solid support surface prior to
the producing of the fragments.
13. The method of claim 12, wherein the transposases are removed
from the modified nucleic acid polymer prior to the attaching of
the modified nucleic acid polymer to the solid support surface.
14. The method of claim 12, wherein the transposases are removed
from the modified nucleic acid polymer after the attaching of the
modified nucleic acid polymer to the solid support surface.
15. The method of claim 14, wherein the modified nucleic acid
polymer is attached to the solid support surface via binding of at
least one transposase to the surface.
16. The method of claim 1, wherein the determining of nucleotide
sequences comprises nanopore sequencing.
17. The method of claim 1, wherein step (a) comprises modifying a
plurality of different target nucleic acid polymers to produce a
mixture of modified nucleic acid polymers, wherein each of the
modified nucleic acid polymers comprises a plurality of sequence
regions from an individual target nucleic acid polymer of the
plurality of different target nucleic acid polymers.
18. The method of claim 17, wherein step (c) comprises producing
representations of the nucleotide sequences for the target nucleic
acid polymers based on the nucleotide sequences from the fragments
and the relative distances between the locations on the solid
support surface.
19. The method of claim 1, wherein the solid support surface
comprises an interior surface of a flow cell.
20. The method of claim 1, further comprising determining haplotype
phase for polymorphisms occurring in the nucleotide sequences for
different fragments released from the modified nucleic acid
polymer.
21. A method of sequencing a target nucleic acid polymer,
comprising (a) modifying a target nucleic acid polymer to produce a
modified nucleic acid polymer, wherein the modified nucleic acid
polymer comprises a plurality of sequence regions from the target
nucleic acid polymer; (b) attaching the modified nucleic acid
polymer to a region on a solid support surface; (c) producing
fragments of the modified nucleic acid polymer that is attached to
the solid support surface, wherein the fragments are attached to
locations at the region of the solid support surface; (d)
determining nucleotide sequences from the fragments by detecting
the fragments at the locations; and (e) producing a representation
of the nucleotide sequence for the target nucleic acid polymers
based on the nucleotide sequences from the fragments and the
relative distances between the locations on the solid support
surface.
22. A method of sequencing a target nucleic acid polymer,
comprising (a) adding inserts into a target nucleic acid polymer to
form a modified nucleic acid polymer comprising a plurality of
internal inserts; (b) producing fragments of the modified nucleic
acid polymer in a fluid that is in contact with a solid support
surface, thereby releasing fragments that each comprise at least a
portion of the inserts having the priming sites; (c) capturing the
fragments from the fluid randomly at locations on a solid support
surface; (d) determining nucleotide sequences from the fragments by
detecting the fragments at the locations; and (e) producing a
representation of the nucleotide sequence for the target nucleic
acid polymer based on the nucleotide sequences from the fragments
and the relative distances between the locations on the solid
support surface.
23. A method of sequencing a target nucleic acid polymer,
comprising (a) adding inserts into a target nucleic acid polymer to
form a modified nucleic acid polymer comprising a plurality of
internal inserts, wherein the inserts have priming sites; (b)
producing fragments of the modified nucleic acid polymer in a fluid
that is in contact with a solid support surface, thereby releasing
fragments that each comprise at least a portion of the inserts
having the priming sites; (c) capturing the fragments from the
fluid randomly at locations on a solid support surface; (d)
determining nucleotide sequences from the fragments by extension of
primers hybridized to the priming sites at the locations; and (e)
producing a representation of the nucleotide sequence for the
target nucleic acid polymer based on the nucleotide sequences from
the fragments and the relative distances between the locations on
the solid support surface.
24. A method of sequencing a target nucleic acid polymer,
comprising (a) adding inserts into a target nucleic acid polymer to
form a modified nucleic acid polymer comprising a plurality of
internal inserts; (b) attaching the modified nucleic acid polymer
to a solid support surface; (c) producing fragments of the modified
nucleic acid polymer that is attached to the solid support surface,
wherein the fragments are attached to locations on the solid
support surface and wherein the fragments each comprise at least a
portion of the inserts; (d) determining nucleotide sequences from
the fragments by detecting the fragments at the locations; and (e)
producing a representation of the nucleotide sequence for the
target nucleic acid polymer based on the nucleotide sequences from
the fragments and the relative distances between the locations on
the solid support surface.
25. A method of determining the source for individual sequences in
a mixture of sequences from different sources, comprising (a)
providing a mixture of target nucleic acid polymers from a
plurality of different sources; (b) modifying the mixture of target
nucleic acid polymers to produce a mixture of modified nucleic acid
polymers, wherein the mixture of modified nucleic acid polymers
comprises a plurality of sequence regions from the different
sources; (c) producing fragments of the modified nucleic acid
polymers in a vessel having a solid support surface, each fragment
comprising a sequence region from a single one of the different
sources; (d) capturing the fragments randomly at locations of the
solid support surface, under conditions wherein fragments from a
common target nucleic acid polymer preferentially localize to
proximal locations on the solid support surface; (e) determining
nucleotide sequences of the fragments at the locations; and (f)
identifying the nucleotide sequences that are derived from a common
source in the plurality of different sources based on the
nucleotide sequences from the fragments and the relative distances
between the locations on the solid support surface.
26. A method of determining the source for individual sequences in
a mixture of sequences from different sources, comprising (a)
providing a mixture of target nucleic acid polymers from a
plurality of different sources; (b) modifying the mixture of target
nucleic acid polymers to produce a mixture of modified nucleic acid
polymers, wherein the mixture of modified nucleic acid polymers
comprises a plurality of sequence regions from the different
sources; (c) attaching the modified nucleic acid polymers to a
solid support surface; (d) producing fragments of the modified
nucleic acid polymers that are attached to the solid support
surface, wherein fragments from a common source of the plurality of
sources are attached to locations that are proximal on the solid
support surface; (e) determining nucleotide sequences of the
fragments at the locations; and (f) identifying the nucleotide
sequences that are derived from a common source in the plurality of
different sources based on the nucleotide sequences from the
fragments and the relative distances between the locations on the
solid support surface.
27. A method of determining the source for individual sequences in
a mixture of sequences from different sources, comprising (a)
providing a mixture of target nucleic acid polymers from a
plurality of different sources; (b) adding inserts into the target
nucleic acid polymers in the mixture to form a mixture of modified
nucleic acid polymers, each polymer including a plurality of
internal inserts; (c) producing fragments of the modified nucleic
acid polymers in a fluid that is in contact with a solid support
surface, thereby releasing fragments that each include at least a
portion of each of the inserts; (d) capturing the fragments from
the fluid randomly at locations on a solid support surface; (e)
determining nucleotide sequences from the fragments by detecting
the fragments at the locations; and (f) identifying the nucleotide
sequences that are derived from a common source in the plurality of
different sources based on the nucleotide sequences from the
fragments and the relative distances between the locations on the
solid support surface.
28. A method of determining the source for individual sequences in
a mixture of sequences from different sources, comprising (a)
providing a mixture of target nucleic acid polymers from a
plurality of different sources; (b) adding inserts into the target
nucleic acid polymers in the mixture to form a mixture of modified
nucleic acid polymers, each polymer comprising a plurality of
internal inserts; (c) attaching the modified nucleic acid polymer
to a solid support surface; (d) producing fragments of the modified
nucleic acid polymers that are attached to the solid support
surface, wherein fragments from a common source of the plurality of
sources are attached to locations that are proximal on the solid
support surface; (e) determining nucleotide sequences from the
fragments by detecting the fragments at the locations; and (f)
identifying the nucleotide sequences that are derived from a common
source in the plurality of different sources based on the
nucleotide sequences from the fragments and the relative distances
between the locations on the solid support surface.
Description
[0001] This application claims priority to U.S. Application Ser.
No. 61/919,529, filed Dec. 20, 2013 and U.S. Application Ser. No.
61/935,776, filed Feb. 4, 2014, both pending, which are
incorporated herein by reference.
BACKGROUND
[0002] This disclosure relates generally to sequencing nucleic
acids, and more specifically to phasing, error correction and
assembly of sequence information obtained from nucleic acids.
[0003] The efforts of the Human Genome Project opened a broader
window to the human genetic code. The work to further unlock the
human genome is ongoing, for example using high-throughput
sequencing technologies. The HapMap (Haplotype Map) Project is a
global scientific effort directed at discovering genetic variants
that lead to disease by comparing genomic information from people
who do and don't have the disease. Alleles, variable forms of a DNA
sequence for a particular genetic locus, can contain one or more
different genetic variants and identifying haplotypes, or
combinations of alleles at different locations, or loci, on a
particular chromosome is a main focus of the HapMap Project.
Identified haplotypes where the two groups of people differ might
correlate to locations of genetic anomalies that cause the disease
being evaluated. As such, HapMap results will help to describe the
common patterns of genetic variation in humans and whether those
variations are potentially correlated to disease.
[0004] The information gained from these efforts is expected to
provide a valuable tool in helping to decipher the causes or cures
for many diseases and disorders. Unfortunately, the cost in
performing such large scale sequencing is still very high and the
technologies to provide more in depth information, such as single
chromosome haplotyping, phasing of alleles or target sequences,
have been elusive. Thus, there exists a need for additional tools
and technologies to unlock more information from the human genome.
The present disclosure addresses this need and provides other
advantages as well.
BRIEF SUMMARY
[0005] The methods set forth in the present application can be
useful for determining proximity of sequence fragments with respect
to a larger target nucleic acid from which the fragments were
derived. For example, the methods can be used to determine phasing
and to identify haplotypes for a relatively long target nucleic
acid sequence when individual sequence reads are shorter than the
length of the target nucleic acid under evaluation.
[0006] The present disclosure provides a method of sequencing a
target nucleic acid polymer. The method can include the steps of
(a) modifying a target nucleic acid polymer to produce a modified
nucleic acid polymer, wherein the modified nucleic acid polymer
includes a plurality of sequence regions from the target nucleic
acid polymer; (b) producing fragments of the modified nucleic acid
polymer in a vessel having a solid support surface, each fragment
comprising one of the sequence regions; (c) capturing the fragments
randomly at locations in a region of the solid support surface; (d)
determining nucleotide sequences of the sequence regions by
detecting the fragments at the locations; and (e) producing a
representation of the nucleotide sequence for the target nucleic
acid polymer based on the nucleotide sequences from the fragments
and the relative distances between the locations on the solid
support surface.
[0007] Also provided is a method of sequencing a target nucleic
acid polymer that includes the steps of (a) adding inserts into a
target nucleic acid polymer to form a modified nucleic acid polymer
including a plurality of internal inserts; (b) producing fragments
of the modified nucleic acid polymer in a fluid that is in contact
with a solid support surface, thereby releasing fragments that each
include at least a portion of the inserts; (c) capturing the
fragments from the fluid randomly at locations on a solid support
surface; (d) determining nucleotide sequences from the fragments by
detecting the fragments at the locations; and (e) producing a
representation of the nucleotide sequence for the target nucleic
acid polymer based on the nucleotide sequences from the fragments
and the relative distances between the locations on the solid
support surface.
[0008] This disclosure further provides a method of sequencing a
target nucleic acid polymer, that includes the steps of (a)
modifying a target nucleic acid polymer to produce a modified
nucleic acid polymer, wherein the modified nucleic acid polymer
includes a plurality of sequence regions from the target nucleic
acid polymer; (b) attaching the modified nucleic acid polymer to a
region on a solid support surface; (c) producing fragments of the
modified nucleic acid polymer that is attached to the solid support
surface, wherein the fragments are attached to locations at the
region of the solid support surface; (d) determining nucleotide
sequences from the fragments by detecting the fragments at the
locations; and (e) producing a representation of the nucleotide
sequence for the target nucleic acid polymers based on the
nucleotide sequences from the fragments and the relative distances
between the locations on the solid support surface.
[0009] Further provided is method of sequencing a target nucleic
acid polymer that includes the steps of (a) adding inserts into a
target nucleic acid polymer to form a modified nucleic acid polymer
including a plurality of internal inserts; (b) attaching the
modified nucleic acid polymer to a solid support surface; (c)
producing fragments of the modified nucleic acid polymer that is
attached to the solid support surface, wherein the fragments are
attached to locations on the solid support surface and wherein the
fragments each include at least a portion of the inserts; (d)
determining nucleotide sequences from the fragments by detecting
the fragments at the locations; and (e) producing a representation
of the nucleotide sequence for the target nucleic acid polymer
based on the nucleotide sequences from the fragments and the
relative distances between the locations on the solid support
surface.
[0010] The methods set forth in the present application can also be
useful for determining the origin of sequence reads obtained for
mixed samples. For example, the methods can be used to identify
sequence fragments that are derived from a common organism when a
mixture of target nucleic acids from a multiple organisms is
processed as a mixture. Thus, the methods can be used to identify
individual organisms in metagenomic samples. Other samples
containing mixtures of target nucleic acids from different sources
can also be used.
[0011] The present disclosure provides a method of determining the
source for individual sequences in a mixture of sequences from
different sources. The method can include the steps of (a)
providing a mixture of target nucleic acid polymers from a
plurality of different sources; (b) modifying the mixture of target
nucleic acid polymers to produce a mixture of modified nucleic acid
polymers, wherein the mixture of modified nucleic acid polymers
includes a plurality of sequence regions from the different
sources; (c) producing fragments of the modified nucleic acid
polymers in a vessel having a solid support surface, each fragment
comprising a sequence region from a single one of the different
sources; (d) capturing the fragments randomly at locations of the
solid support surface, under conditions wherein fragments from a
common target nucleic acid polymer preferentially localize to
proximal locations on the solid support surface; (e) determining
nucleotide sequences of the fragments at the locations; and (f)
identifying the nucleotide sequences that are derived from a common
source in the plurality of different sources based on the
nucleotide sequences from the fragments and the relative distances
between the locations on the solid support surface.
[0012] Also provided is a method of determining the source for
individual sequences in a mixture of sequences from different
sources, wherein the method includes the steps of (a) providing a
mixture of target nucleic acid polymers from a plurality of
different sources; (b) adding inserts into the target nucleic acid
polymers in the mixture to form a mixture of modified nucleic acid
polymers, each polymer including a plurality of internal inserts;
(c) producing fragments of the modified nucleic acid polymers in a
fluid that is in contact with a solid support surface, thereby
releasing fragments that each include at least a portion of each of
the inserts; (d) capturing the fragments from the fluid randomly at
locations on a solid support surface; (e) determining nucleotide
sequences from the fragments by detecting the fragments at the
locations; and (f) identifying the nucleotide sequences that are
derived from a common source in the plurality of different sources
based on the nucleotide sequences from the fragments and the
relative distances between the locations on the solid support
surface.
[0013] This disclosure further provides a method of determining the
source for individual sequences in a mixture of sequences from
different sources, wherein the method includes the steps of (a)
providing a mixture of target nucleic acid polymers from a
plurality of different sources; (b) modifying the mixture of target
nucleic acid polymers to produce a mixture of modified nucleic acid
polymers, wherein the mixture of modified nucleic acid polymers
includes a plurality of sequence regions from the different
sources; (c) attaching the modified nucleic acid polymers to a
solid support surface; (d) producing fragments of the modified
nucleic acid polymers that are attached to the solid support
surface, wherein fragments from a common source of the plurality of
sources are attached to locations that are proximal on the solid
support surface; (e) determining nucleotide sequences of the
fragments at the locations; and (f) identifying the nucleotide
sequences that are derived from a common source in the plurality of
different sources based on the nucleotide sequences from the
fragments and the relative distances between the locations on the
solid support surface.
[0014] Also provided is a method of determining the source for
individual sequences in a mixture of sequences from different
sources, wherein the method includes the steps of (a) providing a
mixture of target nucleic acid polymers from a plurality of
different sources; (b) adding inserts into the target nucleic acid
polymers in the mixture to form a mixture of modified nucleic acid
polymers, each polymer including a plurality of internal inserts;
(c) attaching the modified nucleic acid polymer to a solid support
surface; (d) producing fragments of the modified nucleic acid
polymers that are attached to the solid support surface, wherein
fragments from a common source of the plurality of sources are
attached to locations that are proximal on the solid support
surface; (e) determining nucleotide sequences from the fragments by
detecting the fragments at the locations; and (f) identifying the
nucleotide sequences that are derived from a common source in the
plurality of different sources based on the nucleotide sequences
from the fragments and the relative distances between the locations
on the solid support surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 shows a diagram of an insert having two transposon
elements attached via a linker (Panel A); formation of looped
complexes between transposases and the linked transposon elements
attached to a nucleic acid polymer (Panel B); and a modified form
of the nucleic acid polymer that includes inserts containing the
linked transposon elements.
[0016] FIG. 2 shows a diagram of a flow cell that has captured
insert-modified nucleic acid polymers at three separate regions
(left panel) and the flow cell following cleavage and denaturation
of the insert-modified nucleic acid polymers (right panel).
[0017] FIG. 3 shows a diagram of cluster clouds resulting from the
nucleic acid fragments captured on the flow cell of FIG. 2 and
subsequent bridge amplification of the captured fragments.
[0018] FIG. 4 shows diagrams of sequence reads aligned with a 50 kb
reference sequence absent knowledge of cluster proximity
information (Panel A); sequence reads aligned with the 50 kb
reference genome sequence where reads from two different genomic
DNA molecules (Panel B); and sequence reads for fragments from one
of the genomic DNA molecules aligned with the 50 kb reference
genome sequence (Panel C).
[0019] FIG. 5 shows attachment of target nucleic acids to a bead
followed by fragmentation of the target nucleic acid on the
bead.
[0020] FIG. 6 shows attachment of a modified nucleic acid to a bead
followed by fragmentation of the target nucleic acid on the
bead.
[0021] FIG. 7 shows modification of a target nucleic acid on a
solid support surface and release of fragments from the surface
into solution.
[0022] FIG. 8 shows one-ended transposition to create a modified
nucleic acid having several inserts.
[0023] FIG. 9 shows a diagram of cluster clouds resulting from the
nucleic acid fragments captured from a metagenomic sample on a flow
cell and subsequently bridge amplified.
[0024] FIG. 10 shows a spatial distribution of sequencing clusters
in a flow cell. The control lane (A), which was prepared without
using the proposed method, shows no correlation among clusters'
spatial locations; they are evenly distributed over the area of the
flow cell. The lane prepared using the proposed method (B) shows
the sequencing clusters forming spatially co-located groups, which
were identified by automated algorithms and assigned to sets (C)
for phasing or assembly based on proximity. All units in
nanometers. The X- and the Y-axis are in nm.
[0025] FIG. 11 shows an example of error correction from two
sequencing reads A and B. Sequencing reads A and B differ from the
reference genome at the same position (C for A substitution). The
clusters which generated reads A and B are 350 .mu.m distant from
one another on the flow cell, which is well beyond what might be
caused by an sequencing artifact, yet within the average radius for
proximal groups (200-300 .mu.m).
DETAILED DESCRIPTION
[0026] Traditional nucleic acid sequencing methods, and so-called
next generation sequencing methods, use what is characterized as a
shotgun approach. Specifically, genomic DNA, which is packaged by
nature into large contiguous polymers called chromosomes, is
fragmented into smaller pieces that are amenable to manipulation
and detection in sequencing methods. One of the difficulties of
this shotgun approach is that by the time the sequences of the
individual fragments have been read, knowledge of their
connectivity and proximity to each other in the chromosome has been
lost. The process of ordering the fragments to arrive at the
sequence of the chromosome is generally referred to as "assembly."
Assembly processes are generally time consuming and require
relatively large computational resources. Sequence and assembly
errors can be a problem depending upon the sequencing methodology
used and the quality of genomic DNA samples under evaluation.
[0027] Moreover, many genomes of interest contain more than one
version of each chromosome. For example, the human genome is
diploid, having two sets of chromosomes--one set inherited from
each parent. Some organisms have polyploid genomes with more than
two sets of chromosomes. Examples of polyploid organisms include
animals, such as salmon, and many plant species such as wheat,
apple, oat and sugar cane. When diploid and polyploid genomes are
fragmented and sequenced in typical shotgun methods, phasing
information, pertaining to the identity of which fragments came
from which set of chromosomes, is lost. This phasing information
can be difficult or impossible to reconstruct using typical shotgun
methods.
[0028] Somewhat similar yet often more complex difficulties can
arise when mixed samples are evaluated. Mixed samples can contain
nucleic acid molecules, such as chromosomes, mRNA transcripts,
plasmids etc., from two or more organisms. Mixed samples having
multiple organisms are often referred to as metagenomic
samples.
[0029] Other examples of mixed samples are different cells or
tissues that although being derived from the same organism have
different characteristics. Examples include cancerous tissues which
may comprise a mixture of healthy cells and cancerous cells,
tissues that may comprise pre-cancerous cells and cancerous cells,
tissue that may comprise two or more different types of cancerous
cells. Indeed there may be a variety of different types of cancer
cells as is the case for cancer samples that have mosaicity.
Another example of different cells derived from a single organism
are mixtures of maternal and fetal cells obtained from a pregnant
female (e.g. from the blood or from tissues). When mixed nucleic
acid samples are fragmented and sequenced in typical shotgun
methods information pertaining to the identity of which fragments
came from which cell, organism or other source is lost. This origin
information can be difficult or impossible to reconstruct using
typical shotgun methods.
[0030] The present disclosure provides modified versions of target
nucleic acids that preserve connectivity information for sequence
regions present in the original target nucleic acids from which
they were produced. Using methods set forth herein, fragments of
the modified nucleic acids can be produced and captured on
localized regions of a solid support surface. In cases where
mixtures of different modified nucleic acids are used, the
fragments produced from each nucleic acid molecule can be localized
to respective regions on the surface (albeit that each fragment
will randomly end up at a location that is not predefined). As such
the proximity of different fragments on the surface can be used to
determine which fragments were derived from a common target nucleic
acid molecule. This information can in turn be used to determine
phasing and haplotyping for fragments derived from longer molecules
or to identify two or more fragments that were derived from a
common cell, organism or other source.
[0031] Methods of the present disclosure can provide benefits of
facilitating assembly, improving error correction, identifying
nucleic acid origin in mixed samples and determining phasing
information. Particular embodiments provide fragments of genomic
DNA (or other target nucleic acids) in an arrangement or
composition that correlates with proximity of the fragment
sequences in a particular chromosome (or other nucleic acid).
Sequencing of the fragments and evaluation of their relative
locations in the arrangement or composition can be used to
facilitate assembly, identify and correct errors in the assembled
sequence, and determine phase for haplotypes or other sequence
features. Sequence and relative proximity information can also be
useful for identifying sequences that were derived from a common
source even though the sequences were identified from many
fragments obtained from a mixture of sources.
[0032] By way of a more specific example, methods are provided to
process long target nucleic acid polymers to introduce insert
elements that subdivide the polymer into linked sections. The
insert elements can provide various capabilities such as priming
sites for amplification and/or sequencing processes, ligands for
capture to surfaces, and/or cleavage sites for fragmenting the
polymer. The polymer having the insert elements can be introduced
into a flow cell, or other vessel, having a surface for capture and
detection of nucleic acid fragments. Fragments of the polymer can
then be produced at or near the surface such that fragments that
are from proximal sections of the polymer end up at sites on the
surface that are proximal to each other. The fragments can
optionally be amplified at the sites and then detected in a
sequencing technique. Fragments within a given distance from one
another will have a significant probability of having come from the
same target nucleic acid polymer and this information can be used
to facilitate assembly, error correction, identification of origin
in mixed samples and phasing.
[0033] As set forth in further detail below, the methods set forth
herein can be applied as an improvement to shotgun sequencing
approaches such as those commercially recognized as next generation
sequencing or set forth in references cited herein.
[0034] Terms used herein will be understood to take on their
ordinary meaning in the relevant art unless specified otherwise.
Several terms used herein and their meanings are set forth
below.
[0035] As used herein, the term "actively transported" refers to
movement of a molecule toward or away from a location due to
non-diffusive forces imposed on the molecule. The location can be a
location on a solid support surface (e.g. on an array).
Non-diffusive forces can be provided by an external source such as
those that produce an electrical or magnetic field, fluid flow, or
chemical gradient. Actively transported molecules can move along
their concentration gradient or against their concentration
gradient. Thus, active transport can include applying energy to
move one or more molecule in a desired direction or to a desired
location on a solid support.
[0036] As used herein, the term "array" refers to a population of
sites that can be differentiated from each other according to
relative location. Different molecules that are at different sites
of an array can be differentiated from each other according to the
locations of the sites in the array. An individual site of an array
can include one or more molecules of a particular type. For
example, a site can include a single target nucleic acid molecule
having a particular sequence or a site can include several nucleic
acid molecules having the same sequence (and/or complementary
sequence, thereof). The sites of an array can be different features
or locations on the same substrate. Exemplary sites include without
limitation, wells in a substrate, beads (or other particles) in or
on a substrate, projections from a substrate, ridges on a substrate
or channels in a substrate. The sites of an array can be separate
substrates each bearing a different molecule. Different molecules
attached to separate substrates can be identified according to the
locations of the substrates on a surface to which the substrates
are associated or according to the locations of the substrates in a
liquid or gel. Exemplary arrays in which separate substrates are
located on a surface include, without limitation, those having
beads in wells.
[0037] As used herein, the term "attached" refers to the state of
two things being joined, fastened, adhered, connected or bound to
each other. For example, an analyte, such as a nucleic acid, can be
attached to a material, such as a surface of a solid support, by a
covalent or non-covalent bond. A covalent bond is characterized by
the sharing of pairs of electrons between atoms. A non-covalent
bond is a chemical bond that does not involve the sharing of pairs
of electrons and can include, for example, hydrogen bonds, ionic
bonds, van der Waals forces, hydrophilic interactions and
hydrophobic interactions. In some embodiments, the attachment
occurs via one or more covalent bonds such that the attachment is
not mediated by any non-covalent bonds
[0038] As used herein, the term "cleavage site" is intended to mean
a moiety in a molecule, such as a linker, that can be modified or
removed to physically separate two other moieties of the molecule.
A cleavage site can be susceptible to modification or removal via
biochemical, chemical, physical or other means.
[0039] As used herein, the term "contiguous," when used in
reference to two transposon elements, is intended to mean the two
transposon elements are covalently attached to each other via a
linker. A linker can attach at or near the 5' ends of the two
transposon elements (see FIG. 1 for an example), at or near the 3'
ends of the two transposons, or at or near the 3' end of one of the
transposons and at or near the 5' end of the other transposon.
Examples of contiguous transposon elements that can be useful are
described in PCT Pub. No. WO 2012/061832; US Pat. App. Pub. No.
2012/0208724, US Pat. App. Pub. No. 2012/0208705 and PCT App. Ser.
No. PCT/US2013/031023, each of which is incorporated herein by
reference.
[0040] As used herein, the term "different", when used in reference
to nucleic acids, means that the nucleic acids have nucleotide
sequences that are not the same as each other. Two or more nucleic
acids can have nucleotide sequences that are different along their
entire length. Alternatively, two or more nucleic acids can have
nucleotide sequences that are different along a substantial portion
of their length. For example, two or more different nucleic acids
can have target nucleotide sequence portions that are different
from each other while also having a universal sequence region that
is the same for the two or more different nucleic acids.
[0041] As used herein, the term "each," when used in reference to a
collection of items, is intended to identify an individual item in
the collection but does not necessarily refer to every item in the
collection. Exceptions can occur if explicit disclosure or context
clearly dictates otherwise.
[0042] As used herein, the term "extension," when used in reference
to a primer is intended to include processes wherein one or more
nucleotides are added to the primer (e.g. via polymerase activity)
or wherein one or more oligonucleotides are added to the primer
(e.g. via ligase activity).
[0043] As used herein, the term "flow cell" is intended to mean a
chamber having a surface across which one or more fluid reagents
can be flowed. Generally, a flow cell will have an ingress opening
and an egress opening to facilitate flow of fluid. Examples of
flowcells and related fluidic systems and detection platforms that
can be readily used in the methods of the present disclosure are
described, for example, in Bentley et al., Nature 456:53-59 (2008),
WO 04/018497; U.S. Pat. No. 7,057,026; WO 91/06678; WO 07/123744;
U.S. Pat. No. 7,329,492; U.S. Pat. No. 7,211,414; U.S. Pat. No.
7,315,019; US 7,405,281, and US 2008/0108082, each of which is
incorporated herein by reference.
[0044] As used herein, the term "forked adapter" is intended to
mean a double stranded nucleic acid having a first end wherein the
two strands are annealed to each other and a second end wherein the
two strands are not annealed to each other. Examples of forked or
Y-shaped adapters are described, for example, in U.S. Pat. No.
7,741,463, which is incorporated herein by reference.
[0045] As used herein, the term "fragment," when used in reference
to a first nucleic acid, is intended to mean a second nucleic acid
having a part or portion of the sequence of the first nucleic acid.
Generally, the fragment and the first nucleic acid are separate
molecules. The fragment can be derived, for example, by physical
removal from the larger nucleic acid, by replication or
amplification of a region of the larger nucleic acid, by
degradation of other portions of the larger nucleic acid, a
combination thereof or the like. The term can be used analogously
to describe sequence data or other representations of nucleic
acids.
[0046] As used herein, the term "haplotype" refers to a set of
alleles at more than one locus inherited by an individual from one
of its parents. A haplotype can include two or more loci from all
or part of a chromosome. Alleles include, for example, single
nucleotide polymorphisms (SNPs), short tandem repeats (STRs), gene
sequences, chromosomal insertions, chromosomal deletions etc. The
term "phased alleles" refers to the distribution of the particular
alleles from a particular chromosome, or portion thereof.
Accordingly, the "phase" of two alleles can refer to a
characterization or representation of the relative location of two
or more alleles on one or more chromosomes.
[0047] As used herein, the term "insert," when used in reference to
a polymer is intended to mean a molecule that is, has been or will
be attached to the polymer. The polymer can be, for example, a
nucleic acid such as DNA, RNA or analog thereof. The molecule can
be, for example, a nucleic acid, an analog thereof, or a molecule
having a nucleic acid moiety or analog thereof.
[0048] As used herein, the term "internal," when used in reference
to a polymer having two ends, is intended to mean at a location in
the polymer that is between the two ends of the polymer. For
example, an insert that is internal to a polymer can be located at
a position that is least 1, 2, 3, 4, 5, 10, 100, 200, 500 or 1000
monomer subunits from the end of the polymer.
[0049] As used herein, the terms "ligand" and "receptor" are
intended to refer to components that specifically bind to each
other to form a complex. Examples of ligands and receptors include,
but are not limited to, polyhistidine (e.g., penta-His and
hexa-His) and nickel; avidin (or analogs thereof such as
streptavidin) and biotin (or analogs thereof such as 2-iminobiotin,
desthiobiotin, NeutrAvidin (Molecular Probes, Eugene, Oreg.),
CaptAvidin (Molecular Probes), and the like); binding proteins and
their substrates (e.g. maltose and maltose binding protein (MBP),
calcium and calcium binding protein/peptide (CBP); antibody and
antigens such as c-MYC, HA, VSV-G, HSV, V5, and FLAG Tag.TM.);
aptamers and their corresponding targets; fluorophores and
anti-fluorophore antibodies; nucleic acids and their complements;
and the like. For purposes of the present disclosure the terms
"ligand" and "receptor" can be used interchangeably unless context
or explicit disclosure indicates otherwise. Thus, for example, an
antibody may be considered a receptor or a ligand relative to an
antigen.
[0050] As used herein, the term "linker" is intended to mean a
chemical bond or moiety that covalently bridges two other moieties.
A linker can be, for example, the sugar-phosphate backbone that
connects nucleotides in a nucleic acid moiety. The linker can
include, for example, one or more of a nucleotide moiety, a nucleic
acid moiety, a non-nucleotide chemical moiety, a nucleotide
analogue moiety, amino acid moiety, polypeptide moiety, or protein
moiety. A linker can be non-amplifiable, for example, by virtue of
containing a non-nucleic acid moiety. Exemplary linkers are set
forth in further detail below and in PCT Pub. No. WO 2012/061832;
US Pat. App. Pub. No. 2012/0208724, US Pat. App. Pub. No.
2012/0208705 and PCT App. Ser. No. PCT/US2013/031023, each of which
is incorporated herein by reference.
[0051] As used herein the term "nucleic acid" can refer to at least
two nucleotide monomers linked together. Examples include, but are
not limited to DNA, such as genomic or cDNA; RNA, such as mRNA,
sRNA or rRNA; or a hybrid of DNA and RNA. As apparent from the
examples below and elsewhere herein, a nucleic acid can have a
naturally occurring nucleic acid structure or a non-naturally
occurring nucleic acid analog structure. A nucleic acid can contain
phosphodiester bonds; however, in some embodiments, nucleic acids
may have other types of backbones, comprising, for example,
phosphoramide, phosphorothioate, phosphorodithioate,
O-methylphosphoroamidite and peptide nucleic acid backbones and
linkages. Nucleic acids can have positive backbones; non-ionic
backbones, and non-ribose based backbones. Nucleic acids may also
contain one or more carbocyclic sugars. The nucleic acids used in
methods or compositions herein may be single stranded or,
alternatively double stranded, as specified. In some embodiments a
nucleic acid can contain portions of both double stranded and
single stranded sequence, for example, as demonstrated by forked
adapters. A nucleic acid can contain any combination of deoxyribo-
and ribo-nucleotides, and any combination of bases, including
uracil, adenine, thymine, cytosine, guanine, inosine, xanthanine,
hypoxanthanine, isocytosine, isoguanine, and base analogs such as
nitropyrrole (including 3-nitropyrrole) and nitroindole (including
5-nitroindole), etc. In some embodiments, a nucleic acid can
include at least one promiscuous base. A promiscuous base can
base-pair with more than one different type of base and can be
useful, for example, when included in oligonucleotide primers or
inserts that are used for random hybridization in complex nucleic
acid samples such as genomic DNA samples. An example of a
promiscuous base includes inosine that may pair with adenine,
thymine, or cytosine. Other examples include hypoxanthine,
5-nitroindole, acylic 5-nitroindole, 4-nitropyrazole,
4-nitroimidazole and 3-nitropyrrole. Promiscuous bases that can
base-pair with at least two, three, four or more types of bases can
be used.
[0052] As used herein, the term "nucleotide sequence" is intended
to refer to the order and type of nucleotide monomers in a nucleic
acid polymer. A nucleotide sequence is a characteristic of a
nucleic acid molecule and can be represented in any of a variety of
formats including, for example, a depiction, image, electronic
medium, series of symbols, series of numbers, series of letters,
series of colors, etc. The information can be represented, for
example, at single nucleotide resolution, at higher resolution
(e.g. indicating molecular structure for nucleotide subunits) or at
lower resolution (e.g. indicating chromosomal regions, such as
haplotype blocks). A series of "A," "T," "G," and "C" letters is a
well-known sequence representation for DNA that can be correlated,
at single nucleotide resolution, with the actual sequence of a DNA
molecule. A similar representation is used for RNA except that "T"
is replaced with "U" in the series.
[0053] As used herein, the term "passively diffuse" is intended to
mean movement of molecules along their concentration gradient.
[0054] As used herein, the term "random" can be used to refer to
the spatial arrangement or composition of locations on a surface.
For example, there are at least two types of order for an array
described herein, the first relating to the spacing and relative
location of features (also called "sites") and the second relating
to identity or predetermined knowledge of the particular species of
molecule that is present at a particular feature. Accordingly,
features of an array can be randomly located such that nearest
neighbor features have random spacing between each other.
Alternatively, the spacing between features can be ordered, for
example, forming a regular pattern such as a rectilinear grid or
hexagonal grid. In another respect, features of an array can be
random with respect to the identity or predetermined knowledge of
the species of analyte (e.g. nucleic acid of a particular sequence)
that occupies each feature independent of whether spacing produces
a random pattern or regular pattern. An array set forth herein can
be ordered in one respect and random in another. For example, in
some embodiments set forth herein a surface is contacted with a
population of nucleic acids under conditions where the nucleic
acids attach at sites that are ordered with respect to their
relative locations but random with respect to knowledge of the
sequence for the nucleic acid species present at any particular
site. Reference to "randomly" capturing different nucleic acids at
locations on a surface is intended to refer to the absence of
knowledge or absence of predetermination regarding which nucleic
acid will be captured at which location (regardless of whether the
locations are arranged in an ordered pattern or not).
[0055] As used herein, the term "region," when used in reference to
a surface, means an area of the surface that is smaller than the
entire area of the surface. The regions can be an area that is
smaller than the entire area of a surface that is exposed or
accessible to a fluid. Generally the term "region" is used to refer
to a continuous, uninterrupted area of a surface, whether or not
the region encompasses surface features, sites, contours etc. A
region can encompass one or more locations to which a nucleic acid
is attached or will be attached.
[0056] As used herein, the term "single species" is intended to
refer to substantially one and only one species of a particular
genera. The term is not necessarily intended to limit the number of
representatives of a single species that are present. For example,
a population of nucleic acid molecules, each molecule having the
same nucleotide sequence, comprise a single species of nucleic
acid. The term "single" in this context is not intended to exclude
the presence of other things that are not within the relevant
genera. For example, a location on a surface that contains a single
species of nucleic acid from a library can include multiple nucleic
acids having the same sequence, will exclude other target nucleic
acids from the library, but need not necessarily exclude any other
non-nucleic acid components. It will be understood that an apparent
single species population can have a small amount of another
species present at a level that is considered by those skilled in
the art to be a negligible level of contamination or artifact for
the particular use of the population. For example, a nucleic acid
cluster, derived from a single template having a first sequence,
will be considered to have an apparent single species if the amount
of any nucleic acid molecules having a second sequence is
sufficiently low to be undetectable or ignored when the first
sequence is detected. Alternatively, an absolute single species
population will have one and only one species.
[0057] As used herein, the term "solid support" refers to a rigid
substrate that is insoluble in aqueous liquid. The substrate can be
non-porous or porous. The substrate can optionally be capable of
taking up a liquid (e.g. due to porosity) but will typically be
sufficiently rigid that the substrate does not swell substantially
when taking up the liquid and does not contract substantially when
the liquid is removed by drying. A nonporous solid support is
generally impermeable to liquids or gases. Exemplary solid supports
include, but are not limited to, glass and modified or
functionalized glass, plastics (including acrylics, polystyrene and
copolymers of styrene and other materials, polypropylene,
polyethylene, polybutylene, polyurethanes, Teflon.TM., cyclic
olefins, polyimides etc.), nylon, ceramics, resins, Zeonor, silica
or silica-based materials including silicon and modified silicon,
carbon, metals, inorganic glasses, optical fiber bundles, and
polymers. Particularly useful solid supports for some embodiments
are located within a flow cell apparatus. Exemplary flow cells are
set forth in further detail below.
[0058] As used herein, the term "source" is intended to include an
origin for a nucleic acid molecule, such as a tissue, cell,
organelle, compartment, or organism. The term can be used to
identify or distinguish an origin for a particular nucleic acid in
a mixture that includes origins for several other nucleic acids. A
source can be a particular organism in a metagenomic sample having
several different species of organisms. In some embodiments the
source will be identified as an individual origin (e.g. an
individual cell or organism). Alternatively, the source can be
identified as a species that encompasses several individuals of the
same type in a sample (e.g. a species of bacteria or other organism
in a metagenomic sample having several individual members of the
species along with members of other species as well).
[0059] As used herein, the term "surface," when used in reference
to a material, is intended to mean an external part or external
layer of the material. The surface can be in contact with another
material such as a gas, liquid, gel, polymer, organic polymer,
second surface of a similar or different material, metal, or coat.
The surface, or regions thereof, can be substantially flat. The
surface can have surface features such as wells, pits, channels,
ridges, raised regions, pegs, posts or the like. The material can
be, for example, a solid support, gel, or the like.
[0060] As used herein, the term "target," when used in reference to
a nucleic acid polymer, is intended to linguistically distinguish
the nucleic acid, for example, from other nucleic acids, modified
forms of the nucleic acid, fragments of the nucleic acid, and the
like. Any of a variety of nucleic acids set forth herein can be
identified as target nucleic acids, examples of which include
genomic DNA (gDNA), messenger RNA (mRNA), copy DNA (cDNA), and
derivatives or analogs of these nucleic acids.
[0061] As used herein, the term "transposase" is intended to mean
an enzyme that is capable of forming a functional complex with a
transposon element-containing composition (e.g., transposons,
transposon ends, transposon end compositions) and catalyzing
insertion or transposition of the transposon element-containing
composition into a target DNA with which it is incubated, for
example, in an in vitro transposition reaction. The term can also
include integrases from retrotransposons and retroviruses.
Transposases, transposomes and transposome complexes are generally
known to those of skill in the art, as exemplified by the
disclosure of US Pat. App. Pub. No. 2010/0120098, which is
incorporated herein by reference. Although many embodiments
described herein refer to Tn5 transposase and/or hyperactive Tn5
transposase, it will be appreciated that any transposition system
that is capable of inserting a transposon element with sufficient
efficiency to tag a target nucleic acid can be used. In particular
embodiments, a preferred transposition system is capable of
inserting the transposon element in a random or in an almost random
manner to tag the target nucleic acid.
[0062] As used herein, the term "transposome" is intended to mean a
transposase enzyme bound to a nucleic acid. Typically the nucleic
acid is double stranded. For example, the complex can be the
product of incubating a transposase enzyme with double-stranded
transposon DNA under conditions that support non-covalent complex
formation. Transposon DNA can include, without limitation, Tn5 DNA,
a portion of Tn5 DNA, a transposon element composition, a mixture
of transposon element compositions or other nucleic acids capable
of interacting with a transposase such as the hyperactive Tn5
transposase.
[0063] As used herein, the term "transposon element" is intended to
mean a nucleic acid molecule, or portion thereof, that includes the
nucleotide sequences that form a transposome with a transposase or
integrase enzyme. Typically, the nucleic acid molecule is a double
stranded DNA molecule. In some embodiments, a transposon element is
capable of forming a functional complex with the transposase in a
transposition reaction. As non-limiting examples, transposon
elements can include the 19-bp outer end ("OE") transposon end,
inner end ("IE") transposon end, or "mosaic end" ("ME") transposon
end recognized by a wild-type or mutant Tn5 transposase, or the R1
and R2 transposon end as set forth in the disclosure of US Pat.
App. Pub. No. 2010/0120098, which is incorporated herein by
reference. Transposon elements can comprise any nucleic acid or
nucleic acid analogue suitable for forming a functional complex
with the transposase or integrase enzyme in an in vitro
transposition reaction. For example, the transposon end can
comprise DNA, RNA, modified bases, non-natural bases, modified
backbone, and can comprise nicks in one or both strands.
[0064] As used herein, the term "universal sequence" refers to a
region of sequence that is common to two or more nucleic acid
molecules where the molecules also have regions of sequence that
differ from each other. A universal sequence that is present in
different members of a collection of molecules can allow capture of
multiple different nucleic acids using a population of universal
capture nucleic acids that are complementary to the universal
sequence. Similarly, a universal sequence present in different
members of a collection of molecules can allow the replication,
amplification, or sequence analysis of multiple different nucleic
acids using a population of universal primers that are
complementary to the universal sequence. Thus a universal capture
nucleic acid or a universal primer includes a sequence that can
hybridize specifically to a universal sequence.
[0065] The embodiments set forth below and recited in the claims
can be understood in view of the above definitions.
[0066] The present disclosure provides a method of sequencing a
target nucleic acid polymer. The method can include the steps of
(a) modifying a target nucleic acid polymer to produce a modified
nucleic acid polymer, wherein the modified nucleic acid polymer
includes a plurality of sequence regions from the target nucleic
acid polymer; (b) producing fragments of the modified nucleic acid
polymer in a vessel having a solid support surface, each fragment
comprising one of the sequence regions; (c) capturing the fragments
randomly at locations in a region of the solid support surface; (d)
determining nucleotide sequences of the sequence regions by
detecting the fragments at the locations; and (e) producing a
representation of the nucleotide sequence for the target nucleic
acid polymer based on the nucleotide sequences from the fragments
and the relative distances between the locations on the solid
support surface.
[0067] This disclosure further provides a method of sequencing a
target nucleic acid polymer, that includes the steps of (a)
modifying a target nucleic acid polymer to produce a modified
nucleic acid polymer, wherein the modified nucleic acid polymer
includes a plurality of sequence regions from the target nucleic
acid polymer; (b) attaching the modified nucleic acid polymer to a
region on a solid support surface; (c) producing fragments of the
modified nucleic acid polymer that is attached to the solid support
surface, wherein the fragments are attached to locations at the
region of the solid support surface; (d) determining nucleotide
sequences from the fragments by detecting the fragments at the
locations; and (e) producing a representation of the nucleotide
sequence for the target nucleic acid polymers based on the
nucleotide sequences from the fragments and the relative distances
between the locations on the solid support surface.
[0068] The present disclosure provides a method of determining the
source for individual sequences in a mixture of sequences from
different sources. The method can include the steps of (a)
providing a mixture of target nucleic acid polymers from a
plurality of different sources; (b) modifying the mixture of target
nucleic acid polymers to produce a mixture of modified nucleic acid
polymers, wherein the mixture of modified nucleic acid polymers
includes a plurality of sequence regions from the different
sources; (c) producing fragments of the modified nucleic acid
polymers in a vessel having a solid support surface, each fragment
comprising a sequence region from a single one of the different
sources; (d) capturing the fragments randomly at locations of the
solid support surface, under conditions wherein fragments from a
common target nucleic acid polymer preferentially localize to
proximal locations on the solid support surface; (e) determining
nucleotide sequences of the fragments at the locations; and (f)
identifying the nucleotide sequences that are derived from a common
source in the plurality of different sources based on the
nucleotide sequences from the fragments and the relative distances
between the locations on the solid support surface.
[0069] Also provided is a method of determining the source for
individual sequences in a mixture of sequences from different
sources, wherein the method includes the steps of (a) providing a
mixture of target nucleic acid polymers from a plurality of
different sources; (b) adding inserts into the target nucleic acid
polymers in the mixture to form a mixture of modified nucleic acid
polymers, each polymer including a plurality of internal inserts;
(c) producing fragments of the modified nucleic acid polymers in a
fluid that is in contact with a solid support surface, thereby
releasing fragments that each include at least a portion of each of
the inserts; (d) capturing the fragments from the fluid randomly at
locations on a solid support surface; (e) determining nucleotide
sequences from the fragments by detecting the fragments at the
locations; and (f) identifying the nucleotide sequences that are
derived from a common source in the plurality of different sources
based on the nucleotide sequences from the fragments and the
relative distances between the locations on the solid support
surface.
[0070] A target nucleic acid that is useful in a method or
composition herein can have a structure and/or origin as set forth
elsewhere herein. Exemplary nucleic acid species that can be
targets herein include, but are not limited to DNA, RNA, peptide
nucleic acid, morpholino nucleic acid, locked nucleic acid, glycol
nucleic acid, threose nucleic acid, mixtures thereof, and hybrids
thereof. In a preferred embodiment, genomic DNA fragments, or
amplified copies thereof, are used as the target nucleic acid. In
another preferred embodiment, mitochondrial or chloroplast DNA is
used. Still other embodiments are targeted to RNA or derivatives
thereof such as mRNA or cDNA. IN some embodiments, target nucleic
acid can be from a single cell. In some embodiments, target nucleic
acid can be from acellular body fluids, for example, plasma or
sputum devoid of cells. In some embodiments, target nucleic acid
can be from circulating tumor cells.
[0071] In some embodiments, the target nucleic acid can include
ribosomal RNA (rRNA) or sequences derived therefrom. For example,
rRNA sequences can be particularly useful for distinguishing
different organisms in a metagenomic sample.
[0072] A target nucleic acid can have any of a variety of
nucleotide sequences. In some embodiments, the target nucleic acid
includes homopolymer sequences. A target nucleic acid can also
include repeat sequences. The repeat unit can be, for example, at
least 2, 5, 10, 20, 30, 40, 50, 100, 250, 500, 1000 nucleotides or
more. Repeat sequences can be repeated, either contiguously or
non-contiguously, any of a variety of times including, for example,
at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20 times or more. The
methods set forth herein are particularly useful for analyzing and
evaluating target nucleic acids having homopolymer and/or repeat
sequences because the true length of these sequence regions can be
determined from sequence assemblies that are derived, at least in
part from proximity information obtained from the methods.
[0073] Some embodiments described herein can utilize a single
target nucleic acid species, present in one copy (i.e. single
molecule) or, alternatively present in multiple copies (i.e. an
ensemble of nucleic acid molecules having the same sequence). Other
embodiments can utilize a plurality of different target nucleic
acid species (i.e. nucleic acid molecules having different
nucleotide species being present in the plurality). Thus, a
plurality of target nucleic acids can include a plurality of the
same target nucleic acids, a plurality of different target nucleic
acids where some target nucleic acids are the same, or a plurality
of target nucleic acids where all target nucleic acids are
different.
[0074] Embodiments that utilize a plurality of target nucleic acids
can be carried out in multiplex formats such that reagents are
delivered simultaneously to the target nucleic acids in the
plurality or the target nucleic acids in the plurality are
manipulated simultaneously (e.g. one or more steps of the methods
set forth herein can be carried out simultaneously on the target
nucleic acids that are in the plurality). Target nucleic acids, or
derivatives of the target nucleic acids (e.g. fragments and/or
amplicons) can be provided in one or more chambers or on an array
surface for convenient multiplex manipulation and/or
evaluation.
[0075] In some embodiments, a plurality of target nucleic acids can
include substantially all of a particular organism's genome. The
plurality of target nucleic acids can include at least a portion of
a particular organism's genome including, for example, at least
about 1%, 5%, 10%, 25%, 50%, 75%, 80%, 85%, 90%, 95%, or 99% of the
genome. In particular embodiments the portion can have an upper
limit that is at most about 1%, 5%, 10%, 25%, 50%, 75%, 80%, 85%,
90%, 95%, or 99% of the genome. Exemplary genomes from which target
nucleic acids can be obtained include, without limitation
prokaryotes (e.g. Escherichia, Bacillus, Serratia, Salmonella,
Staphylococcus, Streptococcus, Clostridium, Chlamydia, Neisseria,
Treponema, Mycoplasma, Borrelia, Legionella, Pseudomonas,
Mycobacterium, Helicobacter, Erwinia, Agrobacterium, Rhizobium, and
Streptomyces genera); Achaea, such as crenarchaeota, nanoarchaeota
or euryarchaeotia; or eukaryotes such as fungi, (for example,
yeasts), plants, protozoans, and animals (including insects (for
example, Drosophila spp.), nematodes (e.g., Caenorhabditis
elegans), and mammals (for example, rat, mouse, monkey, non-human
primate and human)).
[0076] A plurality of target nucleic acids can have a complexity
that is equivalent to at least about 3 Gigabases, which is the size
of the haploid human genome, at least about 2 Gigabases, which is a
representation of at least about 60% of the human genome or at
least about 1 Gigabases, which is a representation of at least
about 30% of the human genome. The complexity of a plurality of
target nucleic acid can be larger or smaller than the human genome
being, for example, at least about 0.1 Gigabases, 0.2 Gigabases,
0.5 Gigabases, 0.8 Gigabases, 1 Gigabases, 1.5 Gigabases, 2
Gigabases, 2.5 Gigabases, 3 Gigabases, 3.5 Gigabases, 4 Gigabases,
4.5 Gigabases, 5 Gigabases or more. Alternatively or additionally,
the complexity or a plurality of nucleic acids used in an
embodiment herein can be no more than about 5 Gigabases, 4
Gigabases, 3 Gigabases, 2 Gigabases, 1 Gigabases, 0.5 Gigabases,
0.1 Gigabases or less.
[0077] In some embodiments a plurality of target nucleic acids
include RNA from a desired organism, examples of which include, but
are not limited to those set forth above. A target nucleic acid
sample can include substantially all or part of the complete
complement of RNA present in the organism. The plurality of target
nucleic acids can include at least a portion of a particular
organism's transcriptome including, for example, at least about 1%,
5%, 10%, 25%, 50%, 75%, 80%, 85%, 90%, 95%, or 99% of the
transcriptome. Alternatively or additionally, the portion can have
an upper limit that is at most about 1%, 5%, 10%, 25%, 50%, 75%,
80%, 85%, 90%, 95%, or 99% of the transcriptome.
[0078] In some embodiments, a target nucleic acid or modified
nucleic acid that is produced by integration of an insert into the
target nucleic acid can be at least 0.1 kb, 1 kb, 2 kb, 3 kb, 4 kb,
5 kb, 6 kb, 7 kb, 8 kb, 9 kb, 10 kb, 15 kb, 20 kb, 25 kb, 30 kb, 35
kb, 40 kb, 45 kb, 50 kb, 55 kb, 60 kb, 65 kb, 70 kb, 75 kb, 80 kb,
85 kb, 90 kb, 95 kb, 100 kb, 150 kb, 200 kb, 250 kb, 300 kb, 350
kb, 400 kb, 450 kb, 500 kb, 550 kb, 600 kb, 650 kb, 700 kb, 750 kb,
800 kb, 850 kb, 900 kb, 950 kb, 1000 kb, 5000 kb, 10000 kb, 20000
kb, 30000 kb, or at least 50000 kb in length. Alternatively or
additionally, the target nucleic acid or modified nucleic acid is
no more than 0.1 kb, lkb, 2 kb, 3 kb, 4 kb, 5 kb, 6 kb, 7 kb, 8 kb,
9 kb, 10 kb, 15 kb, 20 kb, 25 kb, 30 kb, 35 kb, 40 kb, 45 kb, 50
kb, 55 kb, 60 kb, 65 kb, 70 kb, 75 kb, 80 kb, 85 kb, 90 kb, 95 kb,
100 kb, 150 kb, 200 kb, 250 kb, 300 kb, 350 kb, 400 kb, 450 kb, 500
kb, 550 kb, 600 kb, 650 kb, 700 kb, 750 kb, 800 kb, 850 kb, 900 kb,
950 kb, or no more than 1000 kb in length.
[0079] Target nucleic acids may be prepared from nucleic acid
molecules obtained from a single organism or from populations of
nucleic acid molecules obtained from natural sources that include
more than one organism. A target nucleic acid can be from a single
cell; from multiple cells, tissue(s) or bodily fluids of a single
organism; from cells, tissues or bodily fluids of several organisms
of the same species; or from multiple species, as with metagenomic
samples, such as from environmental samples. Sources of nucleic
acid molecules include, but are not limited to, organelles, cells,
tissues, organs, or organisms.
[0080] A target nucleic acid sample can, in some embodiments, be
processed prior to adding inserts or prior to performing other
modifications set forth herein. For example, a target nucleic acid
sample can be amplified prior to adding inserts, prior to attaching
to a bead, prior to attaching to the surface of a solid support, or
prior to binding to transposases. Amplification is particularly
useful when samples are in low abundance or when small amounts of a
target nucleic acid are provided. Methods that amplify the vast
majority of sequences in a genome are referred to as "whole genome
amplification" methods. Examples of such methods include multiple
displacement amplification (MDA), strand displacement amplification
(SDA), or hyperbranched strand displacement amplification, each of
which can be carried out using degenerate primers. Particularly
useful methods are those that are used during sample preparation
methods recommended by commercial providers of whole genome
sequencing platforms (e.g. Illumina Inc., San Diego and Life
Technologies Inc., Carlsbad). Other useful methods are set forth in
U.S. Pat. No. 7,670,810, which is incorporated herein by
reference.
[0081] Targeted amplification can be used to selectively amplify
only a portion of a nucleic acid whether it is a target nucleic
acid, modified nucleic acid, nucleic acid fragment or other nucleic
acid set forth herein. Examples of targeted amplification
techniques include, but are not limited to multiplex PCR,
GoldenGate assay (Illumina Inc., San Diego), rolling circle
amplification and other methods known in the art such as those
described in U.S. Pat. No. 7,670,810; U.S. Pat. No. 6,355,431 or
U.S. Pat. No. 7,582,420, each of which is incorporated herein by
reference. Other useful methods for selective enrichment and,
optionally amplification, of targeted regions of a genome include
targeted probe pullout techniques such as those commercialized by
Illumina Inc. under the TruSeq.TM. brand, by NimbleGen Inc. under
the SeqCap EZ.TM. brand or by Agilent, Inc. under the
SureSelect.TM. brand.
[0082] A target nucleic acid sample can, in some embodiments, be
fragmented prior to adding inserts or prior to performing other
modifications set forth herein. In some embodiments, fragmentation
inherently results from amplification, for example, in cases where
the portion of the template that occurs between sites where
flanking primers hybridize is selectively copied. In other cases
fragmentation can be achieved using chemical, enzymatic or physical
techniques known in the art. Fragments in a desired size range can
be obtained using separation methods known in the art such as gel
electrophoresis or purification using SPRI.RTM. beads (AgenCourt,
Beverly Mass.). Accordingly, fragmentation can be carried out to
obtain target DNA polymers, prior to insert addition, that are at
most about 10 kb, 5 kb, 4 kb, 3 kb, 2 kb, 1 kb, 0.8 kb, 0.6 kb, 0.5
kb, 0.4 kb, 0.2 kb, or 0.1 kb or shorter in length. Alternatively
or additionally, size selection can be used to obtain target
nucleic acid polymers having a maximum size selected from those
exemplified above and a minimum size of at least about 0.1 kb, 0.5
kb, 1 kb, 2 kb, 3, kb, 4 kb, 5 kb, 10 kb or longer in length.
[0083] A method of the present disclosure can include a step of
modifying a target nucleic acid polymer to produce a modified
nucleic acid polymer, wherein the modified nucleic acid polymer
includes a plurality of sequence regions from the target nucleic
acid polymer. Exemplary modifications include, but are not limited
to, binding transposase enzymes to the target nucleic acids to form
transposomes, adding inserts into the target nucleic acids,
attaching the target nucleic acids to a bead or other carrier, or
attaching the target nucleic acids to the surface of a substrate
where fragments will subsequently be captured.
[0084] In particular embodiments a target nucleic acid polymer can
be modified by adding one or more inserts into the polymer. Thus, a
method of the present disclosure can include a step of adding an
insert into a target nucleic acid polymer, thereby preparing a
modified nucleic acid. Some methods of insertion include contacting
an insert, having a transposon element, with a target nucleic acid
in the presence of an enzyme, such as a transposase or integrase,
under conditions sufficient for the integration of the insert into
the target nucleic acid. In some embodiments, addition of the
insert into a target nucleic acid can be non-random. In some
embodiments, inserts having transposon elements can be contacted
with target nucleic acids in the presence of one or more proteins
that inhibit integration at certain sites. For example, inserts can
be inhibited from integrating into genomic DNA comprising proteins,
genomic DNA comprising chromatin, genomic DNA comprising
nucleosomes, or genomic DNA comprising histones.
[0085] A step of adding inserts to a target nucleic acid can be
carried out for a target nucleic acid that is in solution, for
example, as diagramed in FIG. 1. As set forth in further detail
below the solution-phase target nucleic acid can be used to produce
fragments that will subsequently bind to the surface of a solid
support. In an alternative embodiment, a target nucleic acid can be
captured on a bead or other solid-phase carrier such that inserts
are added to the target nucleic acid while it is attached to the
solid-phase carrier. FIG. 5 shows a bead 100 having attached
transposases, a similar bead 110 in the presence of a
solution-phase target nucleic acids and a bead 120 where target
nucleic acids have bound to the transposases on the surface of the
bead. The target nucleic acids can be tagmented on the surface of
the bead. A solid-phase carrier can be made from a solid support
material (i.e. being rigid) or from other insoluble materials
whether or not the materials are rigid or compressible (e.g.
hydrogel beads).
[0086] Another embodiment that can be used to add inserts into
target nucleic acid on solid-phase is shown in FIG. 6. In this
example, bead 200 has attached nucleic acid probes that are
complementary to inserts added into a modified nucleic acid. The
inserts have been added into the modified nucleic acid by
transposases and the modified nucleic acid is bound to bead 210 by
annealing of the probes to the inserts to form a solid-phase,
modified nucleic acid. Transposomes can be present on the modified
nucleic acid when it is bound to the bead (as shown in FIG. 6) or
the transposomes can be removed prior to this binding. The
solid-phase, modified nucleic acid can be fragmented on the bead to
produce bead 220 having solid-phase, nucleic acid fragments.
[0087] Any of a variety of target nucleic acids or modified nucleic
acids set forth herein can be attached to a bead or other solid
phase carrier. Accordingly, steps set forth herein for making and
using a target nucleic acid, modified nucleic acid or nucleic acid
fragment can be carried out before or after solid-phase attachment.
For example, a target nucleic acid can be attached to a bead or
other solid-phase carrier and then the attached target nucleic acid
can be treated with a transposase, integrase or other reagent that
introduces inserts. Furthermore, inserts need not be added to
solid-phase target nucleic acids and instead the solid-phase target
nucleic acids can be fragmented without addition of inserts. A bead
or other solid-phase carrier that is bound to a target nucleic
acid, modified nucleic acid or fragments thereof can be delivered
to a vessel having a surface where nucleic acid fragments will be
sequenced or otherwise detected.
[0088] A further example of adding inserts to a solid-phase target
nucleic acid is shown in FIG. 7. As shown in Panel A, a target
nucleic acid is attached to a surface via linkages at or near the
ends of the target nucleic acid. If desired, attachment can occur
at other points on the target nucleic acid. In panel B,
transposases are bound to the solid-phase target nucleic acid to
form multiple solid-phase transposomes. The target nucleic acid can
be tagmented such that multiple different fragments are released
from the surface as shown in Panel C. The released fragments can
then be recaptured on a region of the surface that is proximal to
the site where the target nucleic acid had been captured. The
captured fragments can be further manipulated and detected using
methods set forth herein.
[0089] Whether using solution-phase or solid-phase target nucleic
acids, inserts can have any of a variety of moieties or portions.
In particular embodiments, inserts can be associated with affinity
tags in order to integrate a transposon element of the insert at a
particular sequence in a target nucleic acid. For example, an
insert may be associated with a protein that targets specific
nucleic acid sequences, e.g., histones, chromatin-binding proteins,
transcription factors, initiation factors, etc., and antibodies or
antibody fragments that bind to particular sequence-specific
nucleic-acid-binding proteins. In an exemplary embodiment, an
insert is associated with an affinity tag, such as biotin; and the
affinity tag is associated with a nucleic-acid-binding protein.
[0090] It will be understood that during integration of some
inserts that bear transposon elements, several consecutive
nucleotides at the integration site of the target nucleic acid are
duplicated in the integrated product. Thus the integrated product
can include a duplicated sequence at each end of the insert region
in the resulting modified nucleic acid, for example as described in
PCT Pub. No. WO 2012/061832; US Pat. App. Pub. No. 2012/0208724, US
Pat. App. Pub. No. 2012/0208705 and PCT App. Ser. No.
PCT/US2013/031023, each of which is incorporated herein by
reference. The duplicated sequence can be used as a host tag. For
example, Tn5 transposases bind target nucleic acids and generate
two nicks in the DNA backbone, 9 bases apart on either strand. The
9 base region provides a host tag that will be present in adjacent
fragments. This tag can be used to confirm that fragments which are
proximal on a surface and which also have the same tag sequence did
indeed come from the same target nucleic acid. Thus, the tag can be
used for error checking, facilitating assembly of fragment
sequences or determining haplotype phase.
[0091] In some embodiments, a plurality of the inserts provided
herein is added into a particular target nucleic acid polymer. Some
embodiments include selecting conditions sufficient to achieve
integration of a plurality of transposon sequences into a target
nucleic acid polymer such that the average distance between each
integrated transposon sequence in the polymer is a certain number
of consecutive nucleotides in the target nucleic acid. In some
embodiments, conditions may be selected so that the distance or
average distance in a target nucleic acid between inserts is at
least about 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, or more
consecutive nucleotides. In some embodiments, the distance or
average distance in a target nucleic acid between inserts is at
least about 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, or
more consecutive nucleotides. In some embodiments, the distance or
average distance in a target nucleic acid between inserts is at
least about 1 kb, 2 kb, 3 kb, 4 kb, 5 kb, 6 kb, 7 kb, 8 kb, 90 kb,
100 kb, or more consecutive nucleotides. In some embodiments, the
distance or average distance in a target nucleic acid between
inserts is at least about 100 kb, 200 kb, 300 kb, 400 kb, 500 kb,
600 kb, 700 kb, 800 kb, 900 kb, 1000 kb, or more consecutive
nucleotides. Alternatively or additionally to the threshold values
set forth above, the distance or average distance in a target
nucleic acid between inserts can be at most about 1000 kb, 500 kb,
100 kb, 10 kb, 5 kb, 1 kb, 500 bases, 100 bases, 50 bases or 10
bases.
[0092] Some embodiments can include copying all or part of the
sequences in a nucleic acid. For example, some embodiments include
hybridizing a primer to a priming site of an insert integrated into
a modified nucleic acid, or fragment thereof. In some such
embodiments, the primer can be hybridized to the priming site and
extended. The copied sequences can include at least a portion of
the target nucleic acid, or fragment thereof. In some embodiments,
the primer can be a sequencing primer. In some embodiments
sequencing data is obtained using the sequencing primer. Some
embodiments of methods set forth herein can include amplifying
sequences that include at least a portion of one or more inserts
and at least a portion of a target nucleic acid, or fragment
thereof. In some embodiments, at least a portion of a target
nucleic acid (or fragment thereof) can be amplified using primers
that hybridize to priming sites of inserts integrated into a target
nucleic acid polymer.
[0093] In particular embodiments, inserts are added into a target
nucleic acid polymer by transposases. A transposase can form a
functional complex with an insert that includes a transposon
element thereby forming a transposome. A transposome formed in this
way is capable of catalyzing a transposition reaction to integrate
the insert into a target nucleic acid polymer. In some such
insertion events, one strand of the transposase recognition site
may be transferred into the target nucleic acid.
[0094] Some embodiments can include the use of a hyperactive Tn5
transposase and a Tn5-type transposase element (see, for example,
Goryshin and Reznikoff, J. Biol. Chem., 273:7367 (1998), which is
incorporated herein by reference), or MuA transposase and a Mu
transposase element comprising R1 and R2 end sequences (see, for
example, Mizuuchi, Cell, 35: 785, (1983) and Savilahti, et al.,
EMBO J., 14: 4893, (1995), each of which is incorporated herein by
reference). Exemplary transposase elements that form a complex with
a hyperactive Tn5 transposase (e.g., EZ-Tn5.TM. Transposase,
Epicentre Biotechnologies, Madison, Wis.) are set forth in PCT Pub.
No. WO 2012/061832; US Pat. App. Pub. No. 2012/0208724, US Pat.
App. Pub. No. 2012/0208705 and PCT App. Ser. No. PCT/US2013/031023,
each of which is incorporated herein by reference.
[0095] More examples of transposition systems that can be used with
certain embodiments provided herein include Staphylococcus aureus
Tn552 (Colegio et al., J. Bacteriol., 183: 2384-8 (2001); Kirby et
al., Mol. Microbiol., 43: 173-86 (2002)), Tyl (Devine & Boeke,
Nucleic Acids Res., 22: 3765-72 (1994) and PCT Pub. No. WO
95/23875), Transposon Tn7 (Craig, Science 271: 1512 (1996); Craig,
Curr Top Microbiol Immunol., 204:27-48 (1996)), Tn/O and IS10
(Kleckner et al., Curr Top Microbiol Immunol., 204:49-82 (1996)),
Mariner transposase (Lampe et al., EMBO J., 15: 5470-9, (1996)),
Tcl (Plasterk, Curr. Topics Microbiol. Immunol., 204: 125-43,
(1996)), P Element (Gloor, Methods Mol. Biol., 260: 97-114,
(2004)), Tn3 (Ichikawa & Ohtsubo, J Biol. Chem. 265:18829-32,
(1990)), bacterial insertion sequences (Ohtsubo & Sekine, Curr.
Top. Microbiol. Immunol. 204: 1-26, (1996)), retroviruses (Brown,
et al., Proc Natl Acad Sci USA, 86:2525-9, (1989)), and
retrotransposon of yeast (Boeke & Corces, Annu Rev Microbiol.
43:403-34, (1989)). More examples include IS5, Tn10, Tn903, IS911,
and engineered versions of transposase family enzymes (Zhang et
al., PLoS Genet. 5:e1000689. Epub 2009 Oct. 16; and Wilson et al J.
Microbiol. Methods 71:332-5 (2007)). The references cited in this
paragraph are each incorporated herein by reference.
[0096] Some embodiments provided herein include inserts having
transposon elements, modified nucleic acid polymers having
transposon elements or nucleic acid fragments having transposon
elements. In some embodiments, a transposon element is present in
an insert along with other moieties set forth herein such as a
linker to a second transposon element, a priming site for
amplification, a priming site for primer extension-based detection
(e.g. SBS detection), a binding moiety and/or a cleavage site. FIG.
1 depicts a schematic of an insert including a transposon element
along with other moieties.
[0097] A transposon element can include two nucleic acid strands
that comprise a specific binding site for a transposase or
integrase. The strands can be fully complementary along their
length (e.g., a double-stranded nucleic acid) or complementary
along at least a portion of their length (e.g. a forked adapter,
adapter with non-complementary overhangs, etc.). An exemplary
embodiment of a double stranded transposon element that has
complementary strands in an annealed portion and non-complementary
strands that form a non-annealed portion is depicted in FIG. 1.
[0098] In particular embodiments, an insert includes two transposon
elements that are linked to each other. A linker can be included in
the insert such that a first transposon element is contiguous with
a second transposon element. A particularly useful insert is one
that forms a "looped" complex as set forth in PCT Pub. No. WO
2012/061832; US Pat. App. Pub. No. 2012/0208724, US Pat. App. Pub.
No. 2012/0208705 and PCT App. Ser. No. PCT/US2013/031023, each of
which is incorporated herein by reference. In such structures a
single insert having contiguous transposon elements binds to two
transposase subunits forming a "looped" complex. The looped complex
can be used to place the insert into a target nucleic acid while
maintaining ordering information of the original target nucleic
acid and without fragmenting the resulting modified nucleic acid
polymer. Insertion of a looped transposon element provides for
adding inserts into a target nucleic acid without necessarily
fragmenting the target nucleic acid. As will be set forth in
further detail below the resulting modified nucleic acid polymer
can be fragmented in a subsequent step.
[0099] Useful linkers can have moieties that include, but are not
limited to, one or more nucleotide, nucleic acid, non-nucleotide
containing chemical moiety, nucleotide analogue, amino acid,
polypeptide, or protein. In preferred embodiments, a linker
comprises a nucleic acid moiety. The linker can include at least
about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
18, 19, 20, or more nucleotides. Alternatively or additionally, a
linker can include at most about 100, 50, 20, 10, 9, 8, 7, 6, 5, 4,
3, 2 or 1 nucleotide(s). In a preferred embodiment, the linker is
single stranded between the double stranded ME ends, for example,
to prevent self-insertion.
[0100] A linker can be non-amplifiable, for example, by virtue of
containing one or more non-nucleic acid moiety. In some cases the
linker will not include any nucleic acid material, being completely
devoid of nucleotides. Examples of non-amplifiable linkers include
synthetic linkers such as those having moieties selected from
alkyl, propyl, PEG; non-natural bases such as IsoC, isoG; or any
group that does not amplify in DNA-based amplification schemes. For
example, transposons containing isoC, isoG pairs can be amplified
with dNTP mixtures lacking a complementary isoG and isoC, ensuring
that no amplification occurs across the inserted transposons.
[0101] In particular embodiments, non-amplifiable linkers can be
introduced between Mosaic end (ME) regions. For example, an insert
can have the following configuration: ME-priming
site-linker-priming site-ME. The priming sites can be the same or
different. For example as shown in the construct exemplified in
FIG. 1, the priming sites can both be P5 priming sites. It will be
understood however, that the construct of FIG. 1 can be modified
such that the two P7 priming sites are attached via the linker or
such that the P5 priming site on one of the forked adapters is
attached to the P7 priming site on the other forked adapter. P5 and
P7 priming sites are described in U.S. Pat. No. 8,563,477, which is
incorporated herein by reference.
[0102] A further method for adding inserts to a target nucleic acid
without necessarily fragmenting the target nucleic acid is
one-ended transposition. One-ended transposition can be used to
nick and directly attach an insert to only one strand of the target
DNA at the site of transposition. A diagrammatic example is shown
in FIG. 8. Various enzymes, including transposases can be used for
one-ended transposition. For example, Mu, Tn5, and Rag-like
transposase have been shown to display one-ended transposition.
Certain mutants of Mu (e.g. Mu E392Q) show a preference for
one-ended transposition over two-ended transposition (See Haapa et
al. Nucl. Acids Res. 27:2777 (1999), which is incorporated herein
by reference).
[0103] An exemplary method for achieving one-ended transposition is
to use transposase dimers that are the product of mixing active and
inactive transposase monomers. Inactive monomers can be created by
mutagenesis, chemical modification or both. An appropriate ratio of
active and inactive monomers for achieving an appropriate level of
one-ended transposition can be determined based on statistical
estimation (e.g. Poisson distribution) and/or titration assays. In
particular embodiments, a transposase dimer can be formed from a
mixture of active and inactive monomers that contains at most 50%,
25%, 10%, 5%, 1%, 0.1% or 0.01% active monomer.
[0104] Another method for achieving one-ended transposition is to
use a mixture of reactive and non-reactive transposon elements
along with an active transposase dimer. Exemplary non-reactive
transposon elements include those that are blocked at the 3' end
(e.g. via a dideoxy nucleotide at the 3' end or an extension
blocking moiety at the 3' end). In particular embodiments, a
transposon dimer can be formed from a mixture of reactive and
non-reactive transposon elements that contains at most 50%, 25%,
10%, 5%, 1%, 0.1% or 0.01% reactive elements.
[0105] A further method that is contemplated for achieving
one-ended transposition is to use a monomeric transposome.
Monomeric transposomes are contemplated to result from modification
or removal of dimerization contacts on a transposase protein.
Removal can be achieved by mutagenesis of the monomer to delete a
portion of the protein structure that forms the dimer contact
and/or by point mutation to modify amino acids that participate in
dimerization. Alternatively or additionally, the point of dimer
contact can be modified by chemical modification (e.g. at a native
amino acid that is present in the dimer contact region or at a
mutated amino acid, such as reactive cysteine or lysine, that is
introduced in the dimer contact region).
[0106] An insert used in a method or composition herein can include
one or more priming site. In some embodiments, an insert contains a
single type of priming site. Alternatively, an insert can include
at least one, two or more priming sites. The orientation of the
priming sites in such embodiments can be such that a primer
hybridizing to the first priming site and a primer hybridizing to
the second priming site are in the same orientation, or in
different orientations. In one embodiment, the priming site
sequence in the insert can be complementary to a primer used for
amplification. Alternatively or additionally, the priming site
sequence is complementary to a primer used for sequencing or other
primer extension-based detection technique. In other embodiments
two priming sites can be present in the insert, a first priming
site that is complementary to an amplification primer and a second
priming site that is complementary to a primer used for sequencing
or other primer extension-based detection technique.
[0107] In some embodiments an insert includes a first priming site
and a second priming site wherein one or more other moieties are
disposed between the priming sites such as a cleavage site, binding
moiety, linker or other moiety set forth below or elsewhere herein.
Such embodiments can use a forked or Y-shaped adapter design useful
for directional sequencing, as described in U.S. Pat. No.
7,741,463. An example is shown in FIG. 1.
[0108] In some embodiments, it can be advantageous to use inserts
that have universal priming sites. For example, a target nucleic
acid can be modified to include inserts that include pairs of
universal priming sites, one on each strand. Universal priming
sites can have various applications, such as serving as
hybridization spots for primers used in amplifying, sequencing,
and/or identifying target nucleic acids. When two priming sites are
used, the first and second universal priming sites can be the same,
substantially similar, similar, or different. In some embodiments,
in order to prepare a target nucleic acid to include a first
universal priming site (complementary to a first primer) and a
second universal priming site (complementary to a second primer), a
transposon element of an insert will include a first transposase
recognition site and a second transposase recognition site,
separated by a linker. The first priming site can include sequences
that are the reverse complement of sequences within the second
primer. In some embodiments, the first primer site comprises
sequences having dyad symmetry to sequences within the second
primer. In some embodiments, the first primer site comprises
sequences having C2 symmetry to sequences within the second primer.
A plurality of inserts may be inserted into a target nucleic acid
by transposition in the presence of a transposase. The incorporated
sequences may be cleaved to yield a plurality of target nucleic
acid fragments, each comprising the first priming site and second
priming site.
[0109] A first universal priming site and a second universal
priming site can be incorporated into each target nucleic acid by a
variety of methods. For example, target nucleic acids can be
amplified using a first priming site and second priming site using
tailed-oligonucleotides. As is understood in the art, a
tailed-oligonucleotide can include sequences complementary to a
primer site and additional sequences. In an example embodiment, a
first tailed-oligonucleotide comprises sequences complementary to a
first priming site and sequences for a first universal priming
site, and a second tailed-oligonucleotide comprises sequences
complementary to a second priming site and sequences for a second
universal priming site. Further examples are set forth in PCT Pub.
No. WO 2012/061832; US Pat. App. Pub. No. 2012/0208724, US Pat.
App. Pub. No. 2012/0208705 and PCT App. Ser. No. PCT/US2013/031023,
each of which is incorporated herein by reference. As will be
understood, nucleic acid sequences comprising a first universal
primer site and second universal primer site may be used in further
sequencing methods.
[0110] An insert used in a method or composition of the present
disclosure can include one or more cleavage sites. A modified
nucleic acid polymer that includes an insert can then be cleaved at
the cleavage site to produce fragments of the modified nucleic acid
polymer. Cleavage sites that are susceptible to biochemical,
chemical, physical or other cleavage mechanisms can be used. In
some embodiments, a fragmentation site can include a nucleotide or
nucleotide sequence that may be fragmented by various means. For
example, a fragmentation site may be a substrate for an enzyme,
such as a nuclease. Restriction endonuclease sites having
nucleotide sequences that are specifically susceptible to cleavage
with a respective restriction endonuclease can be particularly
useful.
[0111] In another example, a fragmentation site can contain at
least one ribonucleotide in a nucleic acid that may otherwise
comprise deoxyribonucleotides and may be cleaved with an RNAse.
Chemical cleavage agents capable of selectively cleaving the
phosphodiester bond between a deoxyribonucleotide and a
ribonucleotide can be used including, for example, metal ions such
as rare-earth metal ions (e.g., La.sup.3+, particularly Tm.sup.3+,
Yb.sup.3+ or Lu.sup.3+, Fe(3) or Cu(3)), or exposure to elevated
pH.
[0112] In another example, a cleavage site can include one or more
recognition sequences for a nickase, that is, a nicking
endonuclease that breaks one strand of a double-stranded nucleic
acid. Thus, the fragmentation site can include a first nickase
recognition sequence, and optionally a second nickase recognition
sequence. The first and second nickase recognition sequences can be
the same as each other or different from each other.
[0113] In another example, a cleavage site can include one or more
nucleotide analogues that comprise an abasic site and permits
cleavage at the fragmentation site in the presence of certain
chemical agents, such as polyamine, N,N'-dimethylethylenediamine
(DMED) (see, for example, U.S. Pat. App. Pub. No. 2010/0022403,
which is incorporated herein by reference). In some embodiments, an
abasic site may be created by modification of a uracil nucleotide
within the cleavage site, for example, using a uracil DNA
glycosylase (UDG) enzyme. The polynucleotide strand including the
abasic site may then be cleaved at the abasic site by treatment
with endonuclease (e.g. Endo IV endonuclease, AP lyase, FPG
glycosylase/AP lyase, Endo VIII glycosylase/AP lyase), heat or
alkali. Abasic sites may also be generated at nucleotide analogues
other than deoxyuridine and cleaved in an analogous manner by
treatment with endonuclease, heat or alkali. For example,
8-oxo-guanine can be converted to an abasic site by exposure to FPG
glycosylase. Deoxyinosine can be converted to an abasic site by
exposure to AlkA glycosylase. The abasic sites thus generated may
then be cleaved, typically by treatment with a suitable
endonuclease such as Endo IV or AP lyase (see, for example, U.S.
Patent Publication No. 2011/0014657, which is incorporated herein
by reference).
[0114] In another example, a fragmentation site may include a diol
linkage which permits cleavage by treatment with periodate (e.g.,
sodium periodate). In another example, a fragmentation site may
include a disulfide group which permits cleavage with a chemical
reducing agent, e.g. Tris (2-carboxyethyl)-phosphate hydrochloride
(TCEP).
[0115] In some embodiments, a fragmentation site may include a
photocleavable moiety. Photochemical cleavage can be carried out by
any of a variety of methods that utilize light energy to break
covalent bonds. A site for photochemical cleavage can be provided
by a non-nucleotide chemical moiety in a nucleic acid, such as
phosphoramidite
[4-(4,4'-dimethoxytrityloxy)butyramidomethyl)-1-(2-nitrophenyl)-ethyl]-2--
cyanoethyl-(N,N-diisopropyl)-phosphoramidite) (Glen Research,
Sterling, Va., USA, Cat No. 10-4913-XX).
[0116] In some embodiments, a fragmentation site can include a
peptide, for example, conjugate structure in which a peptide
molecule is linked to a nucleic acid. The peptide molecule can
subsequently be cleaved by a peptidase enzyme of the appropriate
specificity, or by a suitable means of non-enzymatic chemical or
photochemical cleavage. In some embodiments, a conjugate between
peptide and nucleic acid will be formed by covalently linking a
peptide to a nucleic acid, e.g., a strand of a double-stranded
nucleic acid. Conjugates between a peptide and nucleic acid can be
prepared using techniques generally known in the art. In one such
technique the peptide and nucleic acid components of the desired
amino acid and nucleotide sequence can be synthesized separately,
e.g. by standard automated chemical synthesis techniques, and then
conjugated in aqueous/organic solution. By way of example, the
OPeC.TM. system commercially available from Glen Research is based
on the native ligation of an N-terminal thioester-functionalized
peptide to a 5'-cysteinyl oligonucleotide.
[0117] In particular embodiments, fragments of a modified nucleic
acid polymer are produced by amplification of discrete portions of
the polymer. For example, in some embodiments priming sites are
inserted into the modified nucleic acid polymer and regions that
are flanked by the priming sites can be amplified using primers
that hybridize to the priming sites, for example, in a PCR
amplification protocol or similar amplification method. It will be
understood that in some embodiments, such as those that produce
fragments by an amplification technique, a modified nucleic acid
polymer need not include a cleavage site.
[0118] In cases where a modified nucleic acid is attached to a bead
or other solid-phase carrier, fragments can be produced by
destruction of the bead. For example, a hydrogel bead can be melted
or dissolved to release fragments that were attached to the
bead.
[0119] An insert can include one or more ligands. A ligand that is
present in an insert can be a binding partner that is specific for
a particular receptor. For example, the ligand can be specific for
a receptor that is present on the surface of a solid support. As
such, the receptor-ligand binding can facilitate surface capture of
a modified nucleic acid or nucleic acid fragment that contains a
portion of the insert having the ligand. Examples of ligands and
receptors include biotin or polyHis that can bind streptavidin or
nickel, respectively. Other examples include, pairs of ligands and
their receptors known in the art, for example, avidin-biotin,
streptavidin-biotin, and derivatives of biotin, streptavidin, or
avidin, including, but not limited to, 2-iminobiotin,
desthiobiotin, NeutrAvidin (Molecular Probes, Eugene, Oreg.),
CaptAvidin (Molecular Probes), and the like; binding
proteins/peptides, including maltose-maltose binding protein (MBP),
calcium-calcium binding protein/peptide (CBP); antigen-antibody,
including epitope tags, including c-MYC, HA, VSV-G, HSV, V5, and
FLAG Tag.TM., and their corresponding anti-epitope antibodies;
haptens, for example, dinitrophenyl and digoxigenin, and their
corresponding antibodies; aptamers and their corresponding targets;
poly-His tags (e.g., penta-His and hexa-His) and their binding
partners including corresponding immobilized metal ion affinity
chromatography (IMAC) materials and anti-poly-His antibodies;
fluorophores and anti-fluorophore antibodies; nucleic acid strands
and their complementary strands; and the like.
[0120] In some embodiments, an insert can include a reporter
moiety. Useful reporter moieties include any of a variety of
identifiable tags, labels, or groups known in the art. In certain
embodiments, a reporter moiety can emit a signal. Examples of
signals include those that are fluorescent, chemiluminescent,
bioluminescent, phosphorescent, radioactive, calorimetric, or
electrochemiluminescent. Exemplary reporter moieties include
fluorophores, radioisotopes, chromogens, enzymes, antigens
including epitope tags, semiconductor nanocrystals such as quantum
dots, heavy metals, dyes, phosphorescent groups, chemiluminescent
groups, electrochemical detection moieties, binding proteins,
phosphors, rare earth chelates, transition metal chelates,
near-infrared dyes, electrochemiluminescence labels, and mass
spectrometer compatible reporter moieties, such as mass tags,
charge tags, and isotopes. More reporter moieties that may be used
with the methods and compositions described herein include spectral
labels such as fluorescent dyes (e.g., fluorescein isothiocyanate,
Texas red, rhodamine, and the like); radiolabels (e.g., .sup.3H,
.sup.125I, .sup.35S, .sup.14C, .sup.32P, .sup.33P, etc.); enzymes
(e.g., horseradish peroxidase, alkaline phosphatase etc.); spectral
colorimetric labels such as colloidal gold or colored glass or
plastic (e.g. polystyrene, polypropylene, latex, etc.); beads;
magnetic labels; electrical labels; thermal labels; and mass
tags.
[0121] In some embodiments, a plurality of different inserts can be
used, wherein individual inserts can be distinguished by the
presence of a unique barcode sequence. Thus a plurality of
barcode-containing inserts can be added to a target nucleic acid to
produce a modified nucleic acid polymer having a plurality of
unique barcodes throughout. Exemplary barcodes, and methods for
their preparation and use are set forth in PCT Pub. No. WO
2012/061832; US Pat. App. Pub. No. 2012/0208724, US Pat. App. Pub.
No. 2012/0208705 and PCT App. Ser. No. PCT/US2013/031023, each of
which is incorporated herein by reference. In alternative
embodiments, it will be understood that such barcodes need not be
used. This is possible, for example, when the connectivity or
proximity information that is preserved by the methods set forth
herein is sufficient to obtain an accurate representation of a
nucleotide sequence for a target nucleic acid polymer without the
need for the barcoding methods set forth in the above references.
Thus, in particular embodiments, a plurality of inserts used in a
method set forth herein will not include unique sequences (e.g.
barcodes) compared to each other. Instead all of the inserts that
are used in a method set forth herein, present in a modified
nucleic acid polymer of the present disclosure, or present in a
plurality of nucleic acid fragments of the present disclosure can
have the same sequence (i.e. a universal sequence). Accordingly,
some embodiments of the methods set forth herein will be carried
out without distinguishing sequences of individual inserts (i.e.
one insert from another) that may or may not be present in a
modified nucleic acid polymer or fragment thereof
[0122] A method of the present disclosure can include a step of
releasing fragments of a modified nucleic acid polymer into a
fluid. In some embodiments, each of the fragments will include at
least a portion of the inserts that were previously added to the
nucleic acid polymer. In particular embodiments the step can
include (i) contacting the modified nucleic acid polymer with a
solid support surface, and (ii) releasing the fragments of the
modified nucleic acid polymer into the fluid. When a plurality of
different modified nucleic acid polymers are contacted with the
solid support surface it is generally beneficial to do so under
conditions wherein individual modified nucleic acid polymers are
spatially separated from each other. For example, the polymers can
be delivered to vessel having a surface (e.g. the vessel can be a
flow cell having a detection surface) at a relatively dilute
concentration such that the average distance between nearest
neighbor polymers in the vessel or on the surface is in the same
relative range as the average distance that is desired for nearest
neighbor fragments when captured on the surface. Similar spatial
separation can be achieved by delivering modified nucleic acid
polymers that are attached to beads. In the case where released
fragments serve as templates for amplification to form clusters (or
colonies) on the surface, the distance between nearest neighbor
polymers can be in the range of the desired average pitch for
clusters once they have been amplified on the surface.
[0123] In particular embodiments a plurality of different modified
nucleic acid polymers can be delivered to a flow cell (or other
vessel) and allowed to diffuse (actively or passively) through a
fluid that is in contact with a surface to which fragments will
subsequently be attached. Thus, the polymers may be delivered in a
stopped flow condition wherein a solution that carries the polymers
is initially flowed into the flow cell and then the flow is stopped
to allow diffusion. A diagrammatic example of an embodiment where
three different modified nucleic acid polymers are allowed to
diffuse to locations along the surface of a flow cell is shown in
FIG. 2. As exemplified by the figure, the solid support surface can
optionally include a capture moiety that will bind to a binding
partner present on the polymers. Any of a variety of receptors and
ligands set forth herein or otherwise known in the art can be used
for this purpose. Thus, the inserts can include ligands and the
solid support surface can include receptors for the ligands, such
that contacting of the modified nucleic acid polymers with the
solid support surface attaches the modified nucleic acid polymers
to the surface.
[0124] A modified nucleic acid can be attached to a solid-phase
carrier such as a bead and the bead can be delivered to a vessel
having a solid phase surface. FIG. 5 shows an exemplary modified
target nucleic acid on a bead. FIG. 6 shows another example of a
modified target nucleic acid on a bead. A solid-phase carrier
having a target nucleic acid, modified nucleic acid or fragments
thereof can be allowed to contact a solid support surface (e.g. via
gravity settling) and in some cases can be attached to the surface
using receptors and ligands or other means set forth herein.
[0125] Once one or more different modified nucleic acids are
present at or near respective regions of solid support surface,
fragments of the modified nucleic acids can be produced. In some
embodiments, the different modified nucleic acid polymers can be
cleaved such that fragments of the polymers are produced. Cleavage
can occur at cleavage sites that are present in the inserts that
have been integrated into the modified nucleic acid polymers.
Alternatively or additionally, fragments can be produced by
amplifying sequence regions of the modified nucleic acids. For
example, amplification can be carried out using primers that anneal
to priming sites on inserts that have been added to the modified
nucleic acids. Denaturation can optionally be carried out to create
single stranded versions of the fragments. The fragments that are
produced from one or more modified nucleic acid polymers can be
captured randomly at locations on a solid support surface, as set
forth in further detail below.
[0126] As an alternative to passive diffusion of modified nucleic
acid polymers, or fragments thereof, active transport techniques
can be used to move the molecules to a desired location or to
influence the spatial configuration of the molecules. A
particularly useful active transport techniques is electric field
assisted (e-field assist) transport. For example, one or more
regions of an array can be electrically coupled to a power source
to produce an electric charge that attracts target nucleic acid
polymers or fragments thereof. In one configuration, a positive
charge can attract nucleic acids via the negatively charged
sugar-phosphate backbone. Exemplary methods and apparatus for using
e-field assist to attract nucleic acids to surfaces are described
in US Pat. App. Pub. No. 2009/0032401 A1 or U.S. patent application
Ser. No. 13/783,043, each of which is incorporated herein by
reference. Other useful techniques for actively transporting
nucleic acids include, but are not limited to, fluid flow under
positive or negative pressure, gravitational force induced by
centrifugation, movement along chemical or temperature gradients,
and the like.
[0127] The spatial configuration of modified nucleic acid polymers
can be manipulated in a method set forth herein. In particular
embodiments, the polymers can be induced to fold into relatively
compact configurations, for example, using chemical, temperature or
electrical conditions. Exemplary conditions for creating compact
formations include those used to create DNA nanoballs as set forth
in US Pat. App. Pub. No. 2008/0242560 A1 or US Pat. App. Pub. No.
2008/0234136 A1, each of which is incorporated herein by reference.
Alternatively, one or more of the modified nucleic acid polymers
can be stretched or otherwise configured in an elongated
configuration. For example, the polymers can be attached on the
surface (e.g. at or near an end of the polymer) and elongated along
a region of the surface. The fragments derived from the polymers
can eventually be attached to the regions of the surface according
to a method set forth herein. Exemplary techniques for elongating
nucleic acid polymers include, but are not limited to, fluid flow
stretching, weak force stretching, e-field assisted stretching or
other methods known in the art such as those described in US Pat.
App. Pub. No. 2012/0129704 A1, which is incorporated herein by
reference. Accordingly, a method of the invention can include a
step of (i) stretching a modified nucleic acid polymer along a
solid support surface, and (ii) releasing fragments of the modified
nucleic acid polymer into a fluid.
[0128] Conditions can be selected in a method of the present
disclosure to obtain fragments of a desired length. For example,
the length can be influenced by conditions used for attaching
inserts to a target nucleic acid polymer. In cases where the
inserts contain cleavage sites, the length of fragments resulting
from cleavage will be related to the average distance between
inserts in the polymers. The average size of the fragments can also
be influenced by the degree of completion to which a cleavage
reaction is allowed to proceed. A cleavage reaction that goes to
substantial completion will produce fragments that are correlated
with the average distance between cleavage sites in the modified
nucleic acid polymer, whereas cleavage reaction that go to partial
completion will produce fragments of a larger average length than
the average distance between cleavage sites..
[0129] In some embodiments, the absolute or average fragment length
can be at least about 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100,
or more nucleotides. In some embodiments, the absolute or average
fragment length can be at least about 100, 200, 300, 400, 500, 600,
700, 800, 900, 1000, or more nucleotides. In some embodiments, the
absolute or average fragment length can be at least about 1 kb, 2
kb, 3 kb, 4 kb, 5 kb, 6 kb, 7 kb, 8 kb, 90 kb, 100 kb, or more
nucleotides. In some embodiments, the absolute or average fragment
length can be at least about 100 kb, 200 kb, 300 kb, 400 kb, 500
kb, 600 kb, 700 kb, 800 kb, 900 kb, 1000 kb, or more nucleotides.
Alternatively or additionally to the threshold values set forth
above, the absolute or average fragment length can be at most about
1000 kb, 500 kb, 100 kb, 10 kb, 5 kb, 1 kb, 500 bases, 100 bases,
50 bases or 10 bases or less.
[0130] In some embodiments, a target nucleic acid, modified nucleic
acid or nucleic acid fragment can be attached to the surface of a
solid support. Solid supports can be two-or three-dimensional and
can be a planar surface (e.g., a glass slide) or can be shaped.
Useful materials include glass (e.g., controlled pore glass (CPG)),
quartz, plastic (such as polystyrene (low cross-linked and high
cross-linked polystyrene), polycarbonate, polypropylene and
poly(methylmethacrylate)), acrylic copolymer, polyamide, silicon,
metal (e.g., alkanethiolate-derivatized gold), cellulose, nylon,
latex, dextran, gel matrix (e.g., silica gel), polyacrolein, or
composites. Suitable three-dimensional solid supports include, for
example, spheres, microparticles, beads, membranes, slides, plates,
micromachined chips, tubes (e.g., capillary tubes), microwells,
microfluidic devices, channels, filters, or any other structure
suitable for anchoring a nucleic acid. Solid supports can include
planar microarrays or matrices capable of having regions that
include populations of nucleic acids or primers. Examples include
nucleoside-derivatized CPG and polystyrene slides; derivatized
magnetic slides; polystyrene grafted with polyethylene glycol, and
the like.
[0131] Various methods can be used to attach, anchor or immobilize
nucleic acids to the surface of a solid support. The attachment can
be achieved through direct or indirect bonding to the surface. The
bonding can be by covalent linkage. See Joos et al. (1997)
Analytical Biochemistry, 247:96-101; Oroskar et al. (1996) Clin.
Chem., 42:1547-1555; and Khandjian (1986) Mol. Bio. Rep.,
11:107-11, each of which is incorporated herein by reference. A
preferred attachment is direct amine bonding of a terminal
nucleotide of a nucleic acid to an epoxide integrated on the
surface. The bonding also can be through non-covalent linkage. For
example, biotin-streptavidin (Taylor et al. (1991) J. Phys. D:
Appl. Phys., 24:1443, which is incorporated herein by reference)
and digoxigenin with anti-digoxigenin (Smith et al., Science,
253:1122 (1992), which is incorporated herein by reference) are
common tools for anchoring nucleic acids to surfaces.
[0132] Attachment of a nucleic acid to a surface can be via an
intermediate structure such as a bead, particle or gel. Attachment
of nucleic acids to an array via a gel is exemplified by flow cells
available commercially from Illumina Inc. (San Diego, Calif.) or
described in US Pat. App. Publ. Nos. 2010/0111768 A1 or
2012-0270305 A1; or WO 05/065814, each of which is incorporated
herein by reference. Exemplary gels that can be used in the methods
and apparatus set forth herein include, but are not limited to
those having a colloidal structure, such as agarose; polymer mesh
structure, such as gelatin; or cross-linked polymer structure, such
as polyacrylamide, SFA (see, for example, US Pat. App. Pub. No.
2011/0059865 A1, which is incorporated herein by reference) or
PAZAM (see, for example, U.S. Prov. Pat. App. Ser. No. 61/753,833
and WIPO App. Ser. No. PCT/US2013/044305, each of which is
incorporated herein by reference).
[0133] Although the present disclosure sets forth several
embodiments in which a target nucleic acid is modified prior to
being attached to a solid support surface, it will be understood
that a target nucleic acid need not be modified prior to
attachment. For example, a target nucleic acid can be attached to a
solid support prior to being modified by the methods set forth
herein. Transposase treatment can occur after a target nucleic acid
has been attached to a solid support surface. An exemplary
embodiment is diagramed in FIG. 7, where a target nucleic acid is
attached to a surface (Panel A), treated with transposases to
produce a plurality of fragment via tagmentation (Panel B),
resulting in release into solution of several fragments that
contain inserts (Panel C). The fragments can be captured randomly
at sites in a region of the solid support surface. In embodiments
where a plurality of different target nucleic acids are attached to
different regions of the surface, fragments can be released and
captured under conditions where the fragments from each target
nucleic acid randomly end up at different locations within the
respective regions. The captured fragments can be optionally
amplified and/or detected as set forth in further detail
herein.
[0134] For embodiments that utilize transposases to attach inserts
to a target nucleic acid polymer, the transposases may either be
present at the time that the insert-modified nucleic acid polymer
is contacted with the surface of a substrate or the transposases
can be removed from the insert-modified nucleic acid polymer prior
to making the contact. In particular embodiments the transposase
can include a receptor or ligand that binds to a respective ligand
or receptor on the surface of the solid support. Alternatively or
additionally, the ligand or receptor that mediates binding to a
solid support can be present in the insert of the modified nucleic
acid polymer. Thus, the insert can mediate binding to the surface
whether or not transposases are attached to the modified nucleic
acid polymer. Transposases can be removed from nucleic acids using
methods known in the art such as thermal denaturation, chemical
denaturation (e.g. surfactant treatment), or treatment with one or
more proteases.
[0135] In many embodiments, a solid support to which nucleic acids
are attached in a method set forth herein will have a continuous or
monolithic surface. Thus, fragments can attach at spatially random
locations wherein the distance between nearest neighbor fragments
(or nearest neighbor clusters derived from the fragments) will be
variable. The resulting arrays will have a variable or random
spatial pattern of features. Alternatively, a solid support used in
a method set forth herein can include an array of features that are
present in a repeating pattern. In such embodiments, the features
provide the locations to which modified nucleic acid polymers, or
fragments thereof, can attach. Particularly useful repeating
patterns are hexagonal patterns, rectilinear patterns, grid
patterns, patterns having reflective symmetry, patterns having
rotational symmetry, or the like. The features to which a modified
nucleic acid polymer, or fragment thereof, attach can each have an
area that is smaller than about 1 mm.sup.2, 500 .mu.m.sup.2, 100
.mu.m.sup.2, 25 .mu.m.sup.2, 10 .mu.m.sup.2, 5 .mu.m.sup.2, 1
.mu.m.sup.2, 500 nm.sup.2, or 100 nm.sup.2. Alternatively or
additionally, each feature can have an area that is larger than
about 100 nm.sup.2, 250 nm.sup.2, 500 nm.sup.2, 1 .mu.m.sub.2, 2.5
.mu.m.sup.2, 5 .mu.m.sup.2, 10 .mu.m.sup.2, 100 .mu.m.sup.2, or 500
.mu.m.sup.2. A cluster or colony of nucleic acids that result from
amplification of fragments on an array (whether patterned or
spatially random) can similarly have an area that is in a range
above or between an upper and lower limit selected from those
exemplified above.
[0136] For embodiments that include an array of features on a
surface, the features can be discrete, being separated by
interstitial regions. Alternatively, some or all of the features on
a surface can be abutting (i.e. not separated by interstitial
regions). Whether the features are discrete or abutting, the
average size of the features and/or average distance between the
features can vary such that arrays can be high density, medium
density or lower density. High density arrays are characterized as
having features with average pitch of less than about 15 .mu.m.
Medium density arrays have average feature pitch of about 15 to 30
.mu.m, while low density arrays have average feature pitch of
greater than 30 .mu.m. An array useful in the invention can have
feature pitch of, for example, less than 100 .mu.m, 50 .mu.m, 10
.mu.m, 5 .mu.m, 1 .mu.m or 0.5 .mu.m. Alternatively or
additionally, the feature pitch can be, for example, greater than
0.1 .mu.m, 0.5 .mu.m, 1 .mu.m, 5 .mu.m, 10 .mu.m, 50 .mu.m, or 100
.mu.m.
[0137] Several commercially available sequencing platforms rely on
substrates having wells that provide a barrier to the diffusion of
detection reagents (e.g. pyrophosphate in platforms available from
454 LifeSciences (a subsidiary of Roche, Basel Switzerland) or
protons in platforms available from Ion Torrent (a subsidiary of
Life Technologies, Carlsbad Calif.)) during sequence detection
steps. The methods set forth herein can be advantageous for
delivering fragments of a modified nucleic acid to the wells in a
way that phasing or proximity information is preserved.
[0138] A method of the present disclosure can include a step of
capturing fragments from a modified nucleic acid polymer on a solid
support surface. Generally, the fragments have previously been
released from the polymer into a fluid and are then captured from
the fluid such that the fragments randomly end up at particular
locations on the surface. The locations can be on a monolithic or
continuous surface or alternatively the locations can be
prefabricated features on a patterned array. As such, the locations
to which the fragments attach can be random with regard to
predictability or knowledge of where any specific fragment will
attach (i.e. what nucleic acid sequence will be present at a
particular location), whether or not the spatial pattern of the
features is random.
[0139] Fragments that are in a fluid can be transported randomly to
locations on a surface via passive diffusion or active transport.
Exemplary conditions and techniques that can be used for such
transport are known in the art or exemplified herein in the context
of transporting modified nucleic acids to a surface.
[0140] A method of the present disclosure can further include a
step of amplifying fragments at locations on a surface to produce
amplified fragments. The amplified fragments can be detected, for
example, via a nucleic acid sequencing technique as set forth
below. In particular embodiments, the fragments can be amplified
using at least one primer that is attached to the surface. A primer
that is used for amplification can, at least in some
configurations, hybridize to a priming site on an insert. The
primer can be extended to produce the amplified fragments that are
attached to the surface, for example at particular locations.
Solid-phase extension methods can be used as set forth in further
detail below.
[0141] A method of the present disclosure can include a step of
amplifying portions of a target nucleic acid, modified nucleic
acid, or fragments thereof. Any suitable amplification methodology
known in the art can be used. In some embodiments, nucleic acid
fragments are amplified on a solid support. For example, in some
embodiments, the nucleic acid fragments are amplified using bridge
amplification methodologies as exemplified by the disclosures of
U.S. Pat. No. 5,641,658; U.S. Patent Publ. No. 2002/0055100; U.S.
Pat. No. 7,115,400; U.S. Patent Publ. No. 2004/0096853; U.S. Patent
Publ. No. 2004/0002090; U.S. Patent Publ. No. 2007/0128624; and
U.S. Patent Publ. No. 2008/0009420, each of which is incorporated
herein by reference. Bridge amplification methods allow
amplification products to be immobilized on a solid support in
order to form arrays comprised of clusters (or "colonies") of
immobilized nucleic acid molecules. Each cluster or colony on such
an array is formed from a plurality of identical immobilized
polynucleotide strands and a plurality of identical immobilized
complementary polynucleotide strands. The arrays so-formed can be
referred to herein as "clustered arrays". The products of
solid-phase amplification reactions are so-called "bridged"
structures when formed by annealed pairs of immobilized
polynucleotide strands and immobilized complementary strands, both
strands being immobilized on the solid support at the 5' end,
preferably via a covalent attachment. Bridge amplification
methodologies are examples of methods wherein an immobilized
nucleic acid template is used to produce immobilized amplicons.
Other suitable methodologies can also be used to produce
immobilized amplicons from immobilized nucleic acid fragments
produced according to the methods provided herein. For example one
or more clusters or colonies can be formed via solid-phase PCR,
solid-phase MDA, solid-phase RCA etc. whether one or both primers
of each pair of amplification primers are immobilized.
[0142] In other embodiments, target nucleic acids, modified nucleic
acids, or fragments thereof are amplified in solution. For example,
in some embodiments, amplification primers are hybridized to
priming sites of inserts in solution. In other embodiments,
amplification primers are hybridized to the inserts when modified
nucleic acids or fragments thereof are attached to a solid
support.
[0143] It will be appreciated that any of the amplification
methodologies described herein or generally known in the art can be
utilized with universal or target-specific primers to amplify
immobilized DNA fragments. Suitable methods for amplification
include, but are not limited to, the polymerase chain reaction
(PCR), strand displacement amplification (SDA), transcription
mediated amplification (TMA) and nucleic acid sequence based
amplification (NASBA), for example, as described in U.S. Pat. No.
8,003,354, which is incorporated herein by reference. The above
amplification methods can be employed to amplify one or more
nucleic acids of interest. For example, PCR, multiplex PCR, SDA,
TMA, NASBA and the like can be utilized to amplify immobilized
nucleic acid fragments. In some embodiments, primers directed
specifically to the nucleic acid of interest are included in the
amplification reaction.
[0144] Other suitable methods for amplification of nucleic acids
can include oligonucleotide extension and ligation, rolling circle
amplification (RCA) (Lizardi et al., Nat. Genet. 19:225-232 (1998),
which is incorporated herein by reference) and oligonucleotide
ligation assay (OLA) (See generally U.S. Pat. Nos. 7,582,420,
5,185,243, 5,679,524 and 5,573,907; EP 0 320 308 B1; EP 0 336 731
B1; EP 0 439 182 B1; WO 90/01069; WO 89/12696; and WO 89/09835,
each of which is incorporated herein by reference). It will be
appreciated that these amplification methodologies can be designed
to amplify immobilized nucleic acid fragments. For example, in some
embodiments, the amplification method can include ligation probe
amplification or oligonucleotide ligation assay (OLA) reactions
that contain primers directed specifically to the nucleic acid of
interest. In some embodiments, the amplification method can include
a primer extension-ligation reaction that contains primers directed
specifically to the nucleic acid of interest. As a non-limiting
example of primer extension and ligation primers that can be
specifically designed to amplify a nucleic acid of interest, the
amplification can include primers used for the GoldenGate.RTM.
assay (Illumina, Inc., San Diego, Calif.) as exemplified by U.S.
Pat. Nos. 7,582,420 and 7,611,869, each of which is incorporated
herein by reference in its entirety.
[0145] An isothermal amplification technique can be used in a
method of the present disclosure. Exemplary isothermal
amplification methods include, but are not limited to, Multiple
Displacement Amplification (MDA) as exemplified by, for example,
Dean et al., Proc. Natl. Acad. Sci. USA 99:5261-66 (2002) or
isothermal strand displacement nucleic acid amplification as
exemplified by, for example U.S. Pat. No. 6,214,587, each of which
is incorporated herein by reference. Other non-PCR-based methods
that can be used in the present disclosure include, for example,
strand displacement amplification (SDA) which is described in, for
example Walker et al., Molecular Methods for Virus Detection,
Academic Press, Inc., 1995; U.S. Pat. Nos. 5,455,166, and
5,130,238, and Walker et al., Nucl. Acids Res. 20:1691-96 (1992) or
hyperbranched strand displacement amplification which is described
in, for example Lage et al., Genome Research 13:294-307 (2003),
each of which is incorporated herein by reference. Additional
description of amplification reactions, conditions and components
are set forth in U.S. Pat. No. 7,670,810, which is incorporated
herein by reference. Other useful isothermal amplification
techniques include recombinase-facilitated amplification techniques
such as those sold commercially as TwistAmp.TM. kits by TwistDx
(Cambridge, UK). Useful components of recombinase-facilitated
amplification reagent and reaction conditions are set forth in U.S.
Pat. No. 5,223,414 and U.S. Pat. No. 7,399,590, each of which is
incorporated herein by reference. Helicase dependent amplification
can also be used, for example, as described in Xu et al. EMBO Rep
5:795-800 (2004), which is incorporated herein by reference.
[0146] In some embodiments, it may be desirable to perform a
re-seeding step. For example, nucleic acid fragments can be
captured at locations within a region of a surface, replicated on
one or more cycles of an amplification process, the original
fragments and/or amplicons thereof can be released from the
locations, the released nucleic acids can be captured at other
locations in the same region, and the newly captured nucleic acids
can be amplified. In a specific example, a single cycle of bridge
amplification can be carried out for a fragment that was seeded on
a surface and instead of washing away the original template
fragment upon release from the surface, the template fragment can
re-seed the surface at a new location that is proximal to the
location where it had originally seeded. Subsequent rounds of
bridge amplification will allow cluster growth at both the original
seed location and at the re-seed location. Using such methods
replicate colonies can be created at a region of a surface to
provide technical replicates. Analysis of the sequences for the
technical replicates can provide the benefit of error checking. For
example, observed sequence variants that occur in only a subset of
proximal clusters (that are identified as technical replicates) can
be identified as amplification errors, whereas sequence variants
that occur in all clusters that are identified as technical
replicates for a particular fragment are more likely to be true
variants.
[0147] The methods described herein can include a step of
sequencing fragments derived from a target nucleic acid. One
example is sequencing-by-synthesis (SBS). In SBS, extension of a
nucleic acid primer along a nucleic acid template (e.g. a fragment
of a target nucleic acid or amplicon thereof) is monitored to
determine the sequence of nucleotides in the template. The primer
can hybridize to a priming site that is present in an insert as set
forth above. The underlying chemical process can be polymerization
(e.g. as catalyzed by a polymerase enzyme). In a particular
polymerase-based SBS embodiment, fluorescently labeled nucleotides
are added to a primer (thereby extending the primer) in a template
dependent fashion such that detection of the order and type of
nucleotides added to the primer can be used to determine the
sequence of the template. A plurality of different nucleic acid
fragments that have been attached at different locations of an
array using steps set forth herein can be subjected to an SBS
technique under conditions where events occurring for different
templates can be distinguished due to their location in the
array.
[0148] Flow cells provide a convenient format for housing an array
of nucleic acid fragments that is produced by the methods of the
present disclosure and that is subjected to an SBS or other
detection technique that involves repeated delivery of reagents in
cycles. For example, to initiate a first SBS cycle, one or more
labeled nucleotides, DNA polymerase, etc., can be flowed
into/through a flow cell that houses an array of nucleic acid
fragments. Those sites of an array where primer extension (e.g. via
hybridization of the primer to a priming site located on an insert
attached to a nucleic acid fragment) causes a labeled nucleotide to
be incorporated can be detected. Optionally, the nucleotides can
further include a reversible termination property that terminates
further primer extension once a nucleotide has been added to a
primer. For example, a nucleotide analog having a reversible
terminator moiety can be added to a primer such that subsequent
extension cannot occur until a deblocking agent is delivered to
remove the moiety. Thus, for embodiments that use reversible
termination, a deblocking reagent can be delivered to the flow cell
(before or after detection occurs). Washes can be carried out
between the various delivery steps. The cycle can then be repeated
n times to extend the primer by n nucleotides, thereby detecting a
sequence of length n. Exemplary SBS procedures, fluidic systems and
detection platforms that can be readily adapted for use with an
array produced by the methods of the present disclosure are
described, for example, in Bentley et al., Nature 456:53-59 (2008),
WO 04/018497; U.S. Pat. No. 7,057,026; WO 91/06678; WO 07/123744;
U.S. Pat. No. 7,329,492; U.S. Pat. No. 7,211,414; U.S. Pat.
No.7,315,019; U.S. Pat. No. 7,405,281, and US 2008/0108082, each of
which is incorporated herein by reference.
[0149] Other sequencing procedures that use cyclic reactions can be
used, such as pyrosequencing. Pyrosequencing detects the release of
inorganic pyrophosphate (PPi) as particular nucleotides are
incorporated into a nascent nucleic acid strand (Ronaghi, et al.,
Analytical Biochemistry 242(1), 84-9 (1996); Ronaghi, Genome Res.
11(1), 3-11 (2001); Ronaghi et al. Science 281(5375), 363 (1998);
U.S. Pat. No. 6,210,891; U.S. Pat. No. 6,258,568 and U.S. Pat. No.
6,274,320, each of which is incorporated herein by reference). In
pyrosequencing, released PPi can be detected by being converted to
adenosine triphosphate (ATP) by ATP sulfurylase, and the level of
ATP generated can be detected via luciferase-produced photons.
Thus, the sequencing reaction can be monitored via a luminescence
detection system. Excitation radiation sources used for
fluorescence based detection systems are not necessary for
pyrosequencing procedures. Useful fluidic systems, detectors and
procedures that can be used for application of pyrosequencing to
methods of the present disclosure are described, for example, in
WIPO Pat. App. Ser. No. PCT/US11/57111, US 2005/0191698 A1, U.S.
Pat. No. 7,595,883, and U.S. Pat. No. 7,244,559, each of which is
incorporated herein by reference.
[0150] Sequencing-by-ligation reactions are also useful including,
for example, those described in Shendure et al. Science
309:1728-1732 (2005); U.S. Pat. No. 5,599,675; and U.S. Pat. No.
5,750,341, each of which is incorporated herein by reference. Some
embodiments can include sequencing-by-hybridization procedures as
described, for example, in Bains et al., Journal of Theoretical
Biology 135(3), 303-7 (1988); Drmanac et al., Nature Biotechnology
16, 54-58 (1998); Fodor et al., Science 251(4995), 767-773 (1995);
and WO 1989/10977, each of which is incorporated herein by
reference. In both Sequencing-by-ligation and
sequencing-by-hybridization procedures, target nucleic acid
fragments (or amplicons thereof) that are present at sites of an
array are subjected to repeated cycles of oligonucleotide delivery
and detection. Fluidic systems for SBS methods as set forth herein
or in references cited herein can be readily adapted for delivery
of reagents for sequencing-by-ligation or
sequencing-by-hybridization procedures. Typically, the
oligonucleotides are fluorescently labeled and can be detected
using fluorescence detectors similar to those described with regard
to SBS procedures herein or in references cited herein.
[0151] Some embodiments can utilize methods involving the real-time
monitoring of DNA polymerase activity. For example, nucleotide
incorporations can be detected through fluorescence resonance
energy transfer (FRET) interactions between a fluorophore-bearing
polymerase and .gamma.-phosphate-labeled nucleotides, or with
zeromode waveguides (ZMWs). Techniques and reagents for FRET-based
sequencing are described, for example, in Levene et al. Science
299, 682-686 (2003); Lundquist et al. Opt. Lett. 33, 1026-1028
(2008); and Korlach et al. Proc. Natl. Acad. Sci. USA 105,
1176-1181 (2008), the disclosures of which are incorporated herein
by reference.
[0152] Some SBS embodiments include detection of a proton released
upon incorporation of a nucleotide into an extension product. For
example, sequencing based on detection of released protons can use
an electrical detector and associated techniques that are
commercially available from Ion Torrent (Guilford, Conn., a Life
Technologies subsidiary) or sequencing methods and systems
described in US 2009/0026082 A1l; US 2009/0127589 A1; US
2010/0137143 A1; or US 2010/0282617 A1, each of which is
incorporated herein by reference.
[0153] A sequencing step of the present methods can include a
nanopore sequencing technique such as those described in Deamer
& Akeson Trends Biotechnol. 18, 147-151 (2000); Deamer &
Branton, Acc. Chem. Res. 35:817-825 (2002); and Li et al., Nat.
Mater. 2:611-615 (2003), each of which is incorporated herein by
reference. In such embodiments, the target nucleic acid fragment
passes through a nanopore. The nanopore can be a synthetic pore or
biological membrane protein, such as .alpha.-hemolysin. As the
target nucleic acid passes through the nanopore, each base-pair can
be identified by measuring fluctuations in the electrical
conductance of the pore. (U.S. Pat. No. 7,001,792; Soni &
Meller Clin. Chem. 53, 1996-2001 (2007); Healy, Nanomed. 2:459-481
(2007); and Cockroft et al., J. Am. Chem. Soc. 130:818-820 (2008),
each of which is incorporated herein by reference). In some
embodiments, the location of individual nanopores is akin to a site
or feature on the arrays exemplified herein. The proximity of
nanopores to each other can be correlated with the proximity of
fragment sequences they read, for example, to facilitate assembly
of those fragments into the larger sequence from which they were
derived.
[0154] The sequencing steps described herein can be advantageously
carried out in multiplex formats such that multiple different
target nucleic acids are manipulated simultaneously. In particular
embodiments, different target nucleic acids can be treated in a
common reaction vessel or on a surface of a particular substrate.
This allows convenient delivery of sequencing reagents, removal of
unreacted reagents and detection of incorporation events in a
multiplex manner. In embodiments using surface-bound target nucleic
acids, or fragments thereof, the target nucleic acids, or
fragments, can be in an array format. In an array format, fragments
of target nucleic acids can be typically coupled to a surface in a
spatially distinguishable manner, for example, using attachment
techniques set forth herein. The array can include a single copy of
a target nucleic acid fragment at each site (also referred to as a
feature) or multiple copies having the same sequence can be present
at each site or feature. Multiple copies can be produced by
amplification methods such as, bridge amplification or emulsion PCR
as described in further detail herein.
[0155] The methods set forth herein can use arrays having features
at any of a variety of densities including, for example, at least
about 10 features/cm.sup.2, 100 features/cm.sup.2, 500
features/cm.sup.2, 1,000 features/cm.sup.2, 5,000
features/cm.sup.2, 10,000 features/cm.sup.2, 50,000
features/cm.sup.2, 100,000 features/cm.sup.2, 1,000,000
features/cm.sup.2, 5,000,000 features/cm.sup.2, 10.sup.7
features/cm.sup.2, 5.times.10.sup.7 features/cm.sup.2, 10.sup.8
features/cm.sup.2, 5.times.10.sup.8 features/cm.sup.2, 10.sup.9
features/cm.sup.2, 5.times.10.sup.9 features/cm.sup.2, or
higher.
[0156] A method of the present disclosure can include a step of
determining haplotype phase for polymorphisms occurring in the
nucleotide sequences for different fragments released from a
modified nucleic acid polymer. Accordingly, a representation of
nucleotide sequence for a target nucleic acid polymer can include a
representation of haplotype phase for alleles occurring in the
nucleotide sequences for at least two different fragments released
from the modified nucleic acid polymer.
[0157] A method of the present disclosure can include a step of
comparing complementary sequences determined for proximal locations
on the solid support surface to identify sequence errors.
[0158] In accordance with the methods set forth herein, the
relative proximity of any two fragment species on a solid support
can provide information useful for alignment of sequence
information obtained from the two fragments. Specifically, the
distance between clusters, derived from any two given fragments, on
a solid support can be positively correlated with the probability
that the two clusters are from the same target polynucleotide
molecule, as described in greater detail in WO 2012/025250, which
is incorporated herein by reference. Similarly, the distance
between clusters, derived from any two given fragments, on a solid
support can be positively correlated with the probability that the
two clusters are from a common source (since all fragments of a
particular target polynucleotide will have come from the source of
that target polynucleotide).
[0159] As an example, in some embodiments, fragments derived from a
long nucleic acid molecule captured at the surface of a flowcell
occur in a line across the surface of the flowcell (e.g. if the
nucleic acid was stretched out prior to fragmentation or
amplification) or in a cloud on the surface (e.g. if the nucleic
acid was clumped as shown in FIG. 2). Further, a physical map of
the immobilized nucleic acid can then be generated. The physical
map thus correlates the physical relationship of clusters after
immobilized nucleic acid is amplified. Specifically, the physical
map is used to calculate the probability that sequence data
obtained from any two clusters are linked, as described in the
incorporated materials of WO 2012/025250. Alternatively or
additionally, the physical map can be indicative of the genome of a
particular organism in a metagenomic sample. In this latter case
the physical map can indicate the order of sequence fragments in
the organism's genome; however, the order need not be specified and
instead the mere presence of two or more fragments in a common
organism (or other source or origin) can be sufficient basis for a
physical map that characterizes a mixed sample and one or more
organisms therein.
[0160] In some embodiments, the physical map is generated by
imaging the solid support to establish the location of the
immobilized nucleic acid molecules across the surface. In some
embodiments, the immobilized nucleic acid is imaged by adding an
imaging agent to the solid support and detecting a signal from the
imaging agent. In some embodiments, the imaging agent is a
detectable label. Suitable detectable labels, include, but are not
limited to, protons, haptens, radionuclides, enzymes, fluorescent
labels, chemiluminescent labels, and/or chromogenic agents. For
example, in some embodiments, the imaging agent is an intercalating
dye or non-intercalating DNA binding agent. Any suitable
intercalating dye or non-intercalating DNA binding agent as are
known in the art can be used, including, but not limited to those
set forth in U.S. 2012/0282617, which is incorporated herein by
reference.
[0161] In certain embodiments, a plurality of modified nucleic acid
molecules is flowed onto a flowcell comprising a plurality of
nano-channels. As used herein, the term nano-channel refers to a
narrow channel into which a long linear nucleic acid molecule is
stretched. In some embodiments, no more than 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 30, 40, 50, 60
70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900 or no more
than 1000 individual long strands of nucleic acid are stretched
across each nano-channel. In some embodiments the individual
nano-channels are separated by a physical barrier that prevents
individual long strands of target nucleic acid from interacting
with multiple nano-channels. In some embodiments, the solid support
comprises at least 10, 50, 100, 200, 500, 1000, 3000, 5000, 10000,
30000, 50000, 80000 or at least 100000 nano-channels.
[0162] In some embodiments, the nucleic acids have been modified to
include inserts having cleavage sites and the cleavage sites are
cleaved once the nucleic acids have been stretched along the
channel. The resulting fragments can be optionally amplified to
form clusters along the surface of the channel. Contiguity mapping
can then be performed, for example, by following the clusters down
the length of one of these channels. As an example, a flowcell
having 1000 or more nano-channels with mapped immobilized
fragmentation products in the nano-channels can be used to sequence
the genome of an organism with short `positioned` reads. In some
embodiments, mapped immobilized fragmentation products in the
nano-channels can be used to resolve haplotypes. In some
embodiments, mapped immobilized fragmentation products in the
nano-channels can be used to resolve phasing issues.
[0163] In some embodiments, the methods of the above aspects of the
invention can be used for error correction of the sequencing reads.
FIG. 11 shows an example of such error correction. Two sequencing
reads A and B differ from the reference genome at the same position
(C for A substitution). The clusters which generated reads A and B
are 350 .mu.m distant from one another on the flow cell. This
distance is well beyond what might be caused by an sequencing
artifact, yet within the average radius for proximal groups
(200-300 .mu.m). From this, coupled with the fact that the two
reads have identical start-stop positions and their orientations
reversed, it can be inferred that they started as complementary
fragments and that the C mutation shown here is not an artifact of
the sample preparation or sequencing.
[0164] In some embodiments, the methods of the above aspects of the
invention can be used for gene expression analysis. In some
embodiments, the target mRNA is from a single cell. In some
embodiments, mRNA can be captured on beads comprising oligo d(T)
probes.
[0165] Various combinations of the components set forth above in
regard to exemplary reaction mixtures and reaction methods can be
provided in a kit form. Such a kit can include individual
components that are separated from each other, for example, being
carried in separate vessels or packages. A kit can include one or
more sub-combinations of the components set forth herein, the one
or more sub-combinations being separated from other components of
the kit. The sub-combinations can be combinable to create a
reaction mixture set forth herein (or combined to perform a method
set forth herein). In particular embodiments, a sub-combination of
components that is present in an individual vessel or package is
insufficient to perform all steps of a method set forth herein.
However, the kit as a whole can include a collection of vessels or
packages the contents of which can be combined to perform a method
set forth herein.
[0166] A kit can include a suitable packaging material to house the
contents of the kit. The packaging material can be constructed by
well known methods, preferably to provide a sterile,
contaminant-free environment. The packaging materials employed
herein can include, for example, those customarily utilized in
commercial kits sold for use with nucleic acid sequencing systems.
Exemplary packaging materials include, without limitation, glass,
plastic, paper, cardboard, foil, and the like, capable of holding
within fixed limits a component set forth herein.
[0167] The packaging material can include a label which indicates a
particular use for the components. The use for the kit that is
indicated by the label can be one or more of the methods set forth
herein as appropriate for the particular combination of components
present in the kit. For example, a label can indicate that the kit
is useful for adding an insert to a nucleic acid polymer, cleaving
a modified nucleic acid polymer to produce fragments or determining
the sequence of a nucleic acid.
[0168] Instructions for use of the packaged reagents or components
can also be included in a kit. The instructions will typically
include a tangible expression describing reaction parameters, such
as the relative amounts of kit components and sample to be admixed,
maintenance time periods for reagent/sample admixtures,
temperature, buffer conditions, and the like.
[0169] It will be understood that not all components necessary for
a particular reaction need be present in a particular kit. Rather
one or more additional components can be provided from other
sources. The instructions provided with a kit can identify the
additional component(s) that are to be provided and from where they
can be obtained.
[0170] The following examples are intended to illustrate but not
limit the present invention.
EXAMPLE I
Preserving Connectivity Information in Cluster Arrays Using Linked
Transposons to Integrate Inserts into Genomic DNA
[0171] Two transposon elements are linked together as shown in FIG.
1A. Each transposon element forms a forked adapter construct,
having two strands that from an annealed double stranded portion
and a non-annealed portion. The annealed portion includes
complementary portions of each strand that form a mosaic element
(ME). The non-annealed portion includes a P5 priming site near the
5' end of one strand and a P7 priming site near the 3' end of the
other strand. The two transposons are identical and linked together
through the 5' ends of the non-annealed portions (i.e. the 5' ends
of the strands containing the P5 priming sites). The linked
transposon elements bind to respective transposase subunits to form
a transposome complex that is in the form of a looped complex and
several of the looped complexes bind to a target genomic DNA
polymer (FIG. 1B). The linker keeps the target DNA from fragmenting
at the time of transposition (i.e. "tagmentation" is inhibited
despite insertion of the linked transposon elements as shown in
FIG. 1C). As a result of the 5' to 5' linkage, the modified nucleic
acid polymer will include sequence portions from alternate strands
of the target nucleic acid polymer concatenated into a single
polymer strand. The inserts include cleavage sites that are present
in the linker, and optionally a binding moiety is also present in
the linker.
[0172] The target nucleic acid polymers that have been modified to
include the inserts are then loaded into a flow cell and captured
on the surface of the flow cell by a receptor that is specific for
the binding moiety. For example, in the case where the linker
contains a specific nucleic acid sequence the flow cell can include
capture probes with sequences that are complementary to the
specific sequence or alternatively the linker can include a biotin
analog that binds to streptavidin that is attached to the surface
of the flow cell. The insert-modified genomic DNA is attached to
the flow cell surface in double stranded form as shown in FIG. 2.
Under non-flow conditions, individual insert-modified genomic DNA
polymers will bind in a localized region of the surface. The
linkers can then be cleaved and the strands denatured to allow
individual fragments (for example in the range of 200 b to 100 kb)
to diffuse away from each other and seed on the flow cell as shown
on the right hand panel of FIG. 2. The diffusion conditions are
selected to allow the fragments to seed locations that are proximal
to the localized region where the insert-modified genomic DNA
polymer is attached. The diffusion conditions are selected to allow
this localization while preventing the fragments from being too
closely spaced, instead seeding as templates that can form
micron-sized monoclonal clusters in a subsequent bridge
amplification step. Once the templates have been seeded and
bridge-amplified as shown in FIG. 3, sequencing can proceed on a
HiSeq or MiSeq platform (Illumina Inc., San Diego, Calif.) using
standard protocols.
[0173] As exemplified by comparison of the locations of the three
populations of clusters in FIG. 3 to the region where the three
insert-modified genomic DNA polymers bound to the flow cell surface
in FIG. 2, clusters which come from adjacent or overlapping genomic
regions form cluster clouds. Some cluster clouds may be distinct
from other cluster clouds as is exemplified for cloud a which is
distinct from cloud .beta. and from cloud .gamma.. Cluster-clouds
can intermingle without problem, as exemplified for cloud .beta.
and cloud .gamma.. Thus, a flow cell can be clustered at relatively
high densities.
[0174] Sequence analysis is then carried out. During assembly,
adjacent reads are grouped based on a distance metric (e.g.
normalized physical separation between clusters in a flow cell) to
assess whether two reads should be assembled together, considered
phased, or used to correct errors in each other. Nearby reads can
be assembled and phased even across repetitive regions, and
complementary reads which are in close proximity to each other can
be compared against each other for robust error correction.
[0175] Normally, it is unknown which sequence reads obtained for
individual clusters on a flow cell came from a common original
molecule. This is exemplified by the monochromatic collection of
fragment reads 20 aligned against the 50 kb reference sequence 10
in FIG. 4A. However, using the distance information on the flow
cell produced by the method above, reads are grouped into sets
whose distances are consistent with having come from either a first
genomic DNA molecule (light grey fragments 21 in FIG. 4B) or from a
second genomic DNA molecule (dark grey fragments 22 in FIG. 4B).
Accordingly, the set of fragments 22 from the second genomic DNA
molecule can be assembled into a phased contig as shown in FIG.
4C.
[0176] Using the methods exemplified above, homogenous and
heterogeneous loci among the sets can be used to assemble phased
contigs; de novo assembly can be assisted by matching overlaps from
reads that came from the same molecule; and complementary reads
from the same molecule can be used to error check the reads and
confirm rare variants.
EXAMPLE II
Algorithms for Determining Phase for Sequenced Fragments
[0177] Target nucleic acids can be processed to create an array of
fragments, wherein the proximity of fragments to each other on the
array is directly correlated with the probability that the
fragments were produced from the same target nucleic acid molecule.
The processing can be carried out as set forth in Example I or
elsewhere herein.
[0178] In one embodiment, the process starts with target nucleic
acids that have been isolated from a biological source using gentle
preparation methods to minimize damage to genomic DNA (gDNA), so as
to preserve the length of target gDNA molecules to the extent
possible. Each target gDNA is modified to add inserts. A library of
modified gDNA polymers is delivered to a MiSeq flow cell (Illumina,
Inc. San Diego, Calif.) and allowed to diffuse to achieve
separation between library members. The modified gDNAs are
fragmented in the flow cell such that each modified gDNA polymer
produces a sublibrary of gDNA fragments that are captured randomly
at locations on the surface of the flow cell. Conditions are used
to allow fragments from each modified gDNA to be captured within
proximity of each other. Clusters are grown from each fragment at
the respective locations. The clusters are sequenced using standard
MiSeq protocols (Illumina, Inc, San Diego, Calif.).
[0179] The sum of the sequences present in a gDNA fragment
sublibraries can constitute a fraction of the gDNA sequence of the
biological source or it can cover the entirety of the gDNA sequence
at least 1.times.. Typically, the complete set of gDNA fragments
will cover the entirety of the gDNA sequence multiply, for example,
by at least 10.times. or more. The sequences of the gDNA fragments
in the complete set, when aligned to the entire gDNA sequence, can
be abutted, overlapping or gapped.
[0180] Proximity of surface-attached fragments (or clusters derived
from fragments) can be treated as a characterization of the
physical distance between sublibrary members. Although proximity is
a measure of "closeness," the surface-attached fragments (or
clusters) should be spaced far enough apart that they are
resolvable by the sequencing platform detector. This resolution is
desired both for fragments from different gDNA fragment
sublibraries (i.e. inter) and those from the same sublibrary (i.e.
intra).
[0181] For purposes of analysis, members of a given sublibrary are
considered "in proximity" on a surface if the spatial distances
among the members is much less than the spatial distance to the
nearest sublibrary coming from adjacent region of the genome. For
example, looking at FIG. 3, the clusters of the gamma sublibrary
are considered to be "in proximity" to each other despite the fact
that some of the clusters in the gamma sublibrary are closer to
clusters in the nearby beta sublibrary than they are to clusters in
their own sublibrary. The clusters of the gamma sublibrary are
considered to be "in proximity" because the beta sublibrary,
despite appearing to be physically proximal to the gamma sublibrary
on the surface, can be identified by sequence analysis to be
derived from a region of the gDNA sequence that is far away (i.e.
the alpha and gamma sublibraries are derived from regions that are
far from each other in the target genome).
[0182] An algorithm for determining sequences of fragments that are
connected in the target gDNA can include the following steps;
[0183] (a) sequence reads are obtained for clusters on the surface;
[0184] (b) the sequence reads are aligned to a reference genome and
variants are identified; [0185] (c) a sliding window (e.g. 100 Kb)
is used along the genome to reduce the number of reads to be
analyzed; [0186] (d) density based spatial clustering algorithm is
used to identify clouds (i.e. regions) of clusters that are "in
proximity"; [0187] (e) a virtual barcode is assigned to each of the
clouds (i.e. reads derived from the same cloud have the same
barcode and barcodes are unique between different clouds); and
[0188] (f) the barcoded reads are analyzed through the ReFHap
software (Duitama et al. Proceeding of the First ACM International
Conference on Bioinformatics and Computational Biology Pages
160-169 (2010), which is incorporated herein by reference) to
determine phasing of the identified variants.
[0189] An alternative algorithm for determining connectivity can
include steps (a) and (b) of the above algorithm followed by use of
a version of the ReFHap software that has been altered to use a
distance metric. An exemplary distance metric places a greater
weight on two SNPs with a shorter distance from each other (i.e.
proximal) than SNPs which are distant from each other.
EXAMPLE III
Metagenomic Applications
[0190] In this example proximity mapping is used to call sequence
reads as belonging to a single organism in a mixed sample of
various organisms. Thus, the mixed sample can be thought of as
being analogous to the mix of the maternal and paternal haplotypes
that are distinguished in a haplotyping or phasing application.
[0191] A workflow is carried out as follows: [0192] (a) Extract DNA
from the organisms in a mixed sample. [0193] (b) Optionally, enrich
for desired targets or deplete sample of "known and/or
uninteresting" organisms. This can be done for example using
targeted amplification methods to selectively amplify only a
portion of a nucleic acid sample as set forth previously herein.
[0194] (c) Prepare DNA with transpososme complexes as set forth in
Example I or elsewhere herein. [0195] (d) Seed the DNA prepared in
step (c) into flowcell as set forth in Example I or elsewhere
herein. [0196] (e) Clusters/sequence reads in proximity to each
other will have a certain probability to have come from the same
original organism. [0197] (f) Optionally, filter out reads which
align to "known and uninteresting" organisms (i.e. during secondary
sequence analysis), thus reducing the effective "density" of the
noise surrounding clouds of proximal fragments. [0198] (g) This
information can then assist in the building of assembly scaffolds
for the genomes of each organism in the sample.
[0199] An alternative workflow could be used to capture the
organisms themselves at a location in the flowcell, and then
perform the sample prep described in steps (b) through (d) in situ.
In this way substantially all of the recoverable DNA from an
organism is localized to a given spatial location in the flowcell,
instead of just long sections from it.
[0200] A diagram of results that can result is shown in FIG. 9.
Three different cluster clouds derived from three different
organisms in a metagenomic sample are shown. The clouds are
identified as .alpha., .beta., or .gamma.. As exemplified for the
.alpha. and .beta. clouds, when two clouds overlap, the fragments
that align with a known organism (for example, the beta organism)
can be subtracted or removed from the analysis to more clearly
identify the sequences derived from the alpha organism.
EXAMPLE IV
Generating Proximity Reads on Flow Cells
[0201] Promiximity reads on flow cells were generated using 50 ng
of genomic DNA in 10 ul of buffer. Transposition mix components
(Tn5 complexes, MgCl, Tris buffer) were added to the DNA for a
final 20 ul reaction mix, and heated to 55 C for 10 minutes. The
DNA was diluted to 50 pM concentration (based on average fragment
size) and the DNA still bound to transpososomes was loaded onto
flow cell The transposase enzyme was removed from the DNA using
SDS, and the gaps were repaired using a polymerase/ligase mix. The
fragments were allowed to seed to flow cell surface in proximity to
initial capture site. Bridge amplification was performed to amplify
fragments in place to form clonal clusters. Sequencing of the
amplified DNA was performed. Sequencing data was analyzed to
identify proximal groups of clusters, to infer which fragments were
derived from the same original molecule of DNA. This information
was then used to determine the phase of SNPs in the sample and
shown in FIG. 10.
[0202] Human genomic DNA (Coriell sample NA12878) was prepared
using the proposed method and sequenced on an Illumina HiSeq
platform. Twelve indices were added to the sample preparation to
allow for higher density clustering and more accurate
identification of the proximal groups. After alignment to a
reference genome (HG19), data from 2 or 3 lanes were combined and
analyzed for proximal groups of clusters. Information from the
proximal groups was then used to determine the phase of
heterogeneous SNPs in the sample. The phasing data was shown in
Table 1 below.
TABLE-US-00001 TABLE 1 Phasing Data Sample: Human DNA, Coriell
NA12878 2 Hiseq Lanes 3 Hiseq Lanes Clusters passing filter 418M
642M Chr1 clusters 28.5M 42.2M Chr1 clusters in 19.7M 29.9M
proximal groups Chr1 groups 648k 1.0M % of Chr1 SNPs 93% 97% phased
Edit error rate 1.8% 3% Switch error rate 0.5% 0.2%
[0203] Throughout this application various publications, patents or
patent applications have been referenced. The disclosures of these
publications in their entireties are hereby incorporated by
reference in this application in order to more fully describe the
state of the art to which this invention pertains.
[0204] The term "comprising" is intended herein to be open-ended,
including not only the recited elements, but further encompassing
any additional elements.
[0205] Although the invention has been described with reference to
the examples provided above, it should be understood that various
modifications can be made without departing from the invention.
Accordingly, the invention is limited only by the claims.
Sequence CWU 1
1
4135DNAHomo sapiens 1cttaaaaaga gcatgtttta ccttttgtaa attat
35235DNAHomo sapiens 2cttaaaaaga gcatgtttta ccttttgtaa attat
35316DNAHomo sapiens 3gtaaattata tctcaa 16444DNAHomo sapiens
4tacttaaaaa gagcatgttt tacattttgt aaattatatc tcaa 44
* * * * *